Search

Background: The Self-Assessment Psoriasis Area Severity Index (SAPASI) is a patient-administered psoriasis assessment tool for which we present a validated translation from English to Swedish. Methods: Validity was evaluated in this single-centre study using the Psoriasis Area Severity Index (PASI) as the standard. Test-retest reliability was assessed using repeated SAPASI measurements. Results: Significant correlations (P

Storytel is one of the world’s largest subscribed audiobook and ebook streaming services and offers unlimited listening and reading of more than 700 000 titles on a global scale. Its vision is to make the world a more empathetic and creative place with great stories to be shared and enjoyed by anyone, anywhere, and at anytime. Storytel operates in 25 markets around the globe and is headquartered in Stockholm. In summer 2021, Storytel launched a customized student discount offering in several of its markets, targeting audiences at universities and colleges. Logos seized the opportunity to talk to Storytel’s Chief Content Strategy Officer Helena Gustafsson – about stories, global expansion, the wave of audiotainment, and the evolution of literature in a digital era in which books are more accessible than ever.

Atrial fibrillation seems to be overrepresented among patients with primary aldosteronism. The aim of this study was to determine the usefulness of aldosterone to renin ratio as a screening instrument for primary aldosteronism in an atrial fibrillation population with relatively low cardiovascular risk profile. A total of 149 patients 65 pmol/mIU) was found in 15 participants (10.1%). Further investigation of the positive screened participants and confirmatory saline infusion test resulted in a diagnosis of primary aldosteronism in four individuals out of 149 (2.6%). Three out of the four individuals with primary aldosteronism had previously been diagnosed with hypertension, but only one out of the four had uncontrolled blood pressure, that is, >140/90 mmHg. All participants had normal potassium levels. Individuals with increased aldosterone to renin ratio had significantly higher mean systolic and diastolic blood pressure in comparison to participants with normal aldosterone to renin ratio (136 vs. 126 mmHg, p=0.02 and 84 vs. 78 mmHg, p=0.02). These findings suggest that assessment of aldosterone to renin ratio can be useful for identification of underlying primary aldosteronism in patients with diagnosed atrial fibrillation and hypertension in spite of well controlled blood pressure and normokalemia.

Here we present a multipotent neuronal progenitor cell line for toxicity testing as an alternative to primary cultures of mixed cell types from brain tissue. The v-myc immortalised C17.2 cell line, originally cloned from mouse cerebellar neural stem cells, were maintained as monolayer in cell culture dishes in DMEM supplemented with fetal calf serum, horse serum and antibiotics. Different media and exposure scenarios were used to induce differentiation. The optimal condition which generated mixed cultures of neurons and astrocytes included serum-free DMEM:F12 medium with N2 supplements, brain-derived neurotrophic factor and nerve growth factor. The medium was changed every 3rd or 4th day to fresh N2 medium with supplements. After 7days, the culture contained two different morphological cell types, assumed to be neurons and glia cells. The presence of astrocytes and neurons in the culture was confirmed by RT-PCR and Western blot analyses, indicating increased mRNA and protein levels of the specific biomarkers glial fibrillary acidic protein (GFAP) and βIII-tubulin, respectively. Concomitantly, the expression of the neural progenitor cell marker nestin was down-regulated.

Maternal cardiovascular morbidity is increased after hypertensive pregnancies (HTP). The pathways from complicated pregnancies to future cardiovascular disease are complex. The aim of the present study was to test the hypothesis that different cardiovascular mechanisms are changed in women who experienced HTP four decades earlier in comparison to women with normotensive pregnancies.One hundred and five women (50 with hypertensive and 55 with normal pregnancies) were examined with anthropometric measurements; office blood pressure, ambulatory blood pressure and central blood pressure, pulse wave velocity, augmentation index, intimal-media thickness, echocardiography and laboratory measurements. In addition another 204 women were followed-up by a questionnaire regarding their pregnancy 40 years ago, as well as their present health status and medications.Women with HTP had more often diagnosed hypertension when compared with women with normal pregnancies (50 vs. 31%, respectively; P = 0.046), but the groups did not differ in any blood pressure levels. HTP were associated with higher pulse wave velocity (8.8 m/s vs. 7.8 m/s, P = 0.021), and higher levels of P-glucose (5.7 mmol/l vs. 5.2 mmol/l, P = 0.022), P-HbA1c (4.4% vs. 4.2%, P = 0.010) and noradrenaline (2.45 mmol/l vs. 2.11 mmol/l, P = 0.040) when compared with normotensive pregnancies. Women followed up with a questionnaire reported deteriorated cardiovascular health compared to women attending the clinical investigations of the study.HTP are associated with impairment in vascular function and metabolic status 40 years postpartum despite well controlled blood pressure levels.

PurposeThis study aims to describe implementation of simulator‐based medical team training and the effect of this programme on inter‐professional working in an intensive care unit (ICU).Design/methodology/approachOver a period of two years, 90 percent (n=152) of the staff of the general ICU at Karolinska University Hospital, Huddinge, Sweden, received inter‐professional team training in a fully equipped patient room in their own workplace. A case study method was used to describe and explain the planning, formation, and results of the training programme.FindingsIn interviews, the participants reported that the training had increased their awareness of the importance of effective communication for patient safety. The intervention had even had an indirect impact by creating a need to talk, not only about how to communicate efficaciously, but also concerning difficult care situations in general. This, in turn, had led to regular reflection meetings for nurses held three times a week. Examples of better communication in acute situations were also reported. However, the findings indicate that the observed improvements will not last, unless organisational features such as staffing rotas and scheduling of rounds and meetings can be changed to enable use of the learned behaviours in everyday work. Other threats to sustainability include shortage of staff, overtime for staff, demands for hospital beds, budget cuts, and poor staff communication due to separate meetings for nurses and physicians.Originality/valueThe present results broaden our understanding of how to create and sustain an organizational system that supports medical team training.

Perivascular adipose tissue (PVAT) has been shown to produce vasoactive substances and regulate vascular tone. This function of PVAT has been reported to be altered in hypertension. However, the underlying mechanisms are not fully understood. In this study we used age-matched normotensive Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR) as well as Sprague-Dawley rats and tested effects of PVAT on mesenteric small arteries. Vessels were mounted in a Mulvany–Halpern myograph and cumulative concentration–response relations to noradrenaline were determined in the presence or absence of PVAT. We found that PVAT has an anti-contractile effect on mesenteric small vessels, irrespective of strains. A reduced effect of PVAT was observed in SHR compared to WKY rats; the difference between strains was eliminated by 10 μM XE991, a blocker of Kv7 (KCNQ) voltage-dependent potassium channels. The anti-contractile effect of PVAT was not affected by depolarizing smooth muscle cells with high K + solution. Sensitivities to exogenous vasodilators acetylcholine or sodium nitroprusside were not potentiated but reduced in vessels with PVAT. Our results suggest that the reduced anti-contractile effect of PVAT in SHR correlates with a deficiency in Kv7 channels. Diffusion hindrance of PVAT is also a factor that should be considered in investigations on rat mesenteric small arteries.

Cardiac structure and function is related to current blood pressure rather than to previous hypertensive pregnancy

Objective: Women experiencing hypertensive pregnancies have an increased risk for cardiovascular disease. Whether stress increase the risk is unknown. The objective was to test if cardiovascular response to stress and/or perceived stress differed in relation to blood pressure status during pregnancy 40 years earlier. Methods: Cardiovascular response was examined with mental stress test, and perceived stress was evaluated with a questionnaire in 105 women. Results: Resting heart rate was higher, and pulse reactivity was lower in women with previous hypertensive pregnancies. Neither blood pressure nor perceived stress differed. Conclusion: Response to physical or psychological stress is not affected many years after pregnancy.

In this study, a significant increase by 50% in intracellular free calcium concentration ([Ca(2+)](i)) was observed in differentiated human neuroblastoma (SH-SY5Y) cells after exposure to 0.25microM of the fungal metabolite gliotoxin for 72h. Further, the involvement of caspases and calpains was demonstrated to underlie the gliotoxin-induced cytotoxic and neurite degenerative effects. The caspase inhibitor Z-VAD-fmk almost completely reduced the neurite degeneration from 40% degeneration of neurites to 5% as compared to control. Inhibition of calpains with calpeptin significantly attenuated gliotoxin-induced cytotoxicity, determined as reduction in total cellular protein content, from 43% to 14% as compared to control cells. Western blot analyses of alphaII-spectrin breakdown fragments confirmed activity of the proteases, and that alphaII-spectrin was cleaved by caspases in gliotoxin-exposed cells. These results show that calpains and caspases have a role in the toxicity of gliotoxin in differentiated SH-SY5Y cells and that the process may be Ca(2+)-mediated.

Uncoupling protein 3 (UCP3) is a mitochondrial protein with antioxidant properties and its regulation by factors promoting cell-survival may be important for protection of, for instance, neurons in states of oxidative stress. In the present study, we investigated regulatory pathways for UCP3 expression mediated by the neuroprotective hormone insulin-like growth factor type 1 (IGF-1) in human neuroblastoma SH-SY5Y cells. Northern blot analysis and RT-PCR showed that treatment with 10 nm IGF-1 increased the UCP3 mRNA levels 2.5-fold after 5 h. Co-incubation with the phosphatidylinositol 3 (PI3)-kinase inhibitor LY294002 prohibited IGF-1-mediated induction of both UCP3 mRNA and protein in a concentration-dependent manner, with a complete blockage at 1 microm, as shown by RT-PCR and western blot analyses. The mitogen-activated protein (MAP) kinase kinase 1 (MKK1 or MEK) inhibitor PD98059 also decreased the UCP3 mRNA expression at 10 microm, however, this concentration only partly inhibited the protein expression. We conclude that IGF-1 enhanced UCP3 expression at transcriptional level, primarily through the PI3-kinase-dependent pathway and partly through the MAP kinase pathway.

BACKGROUND Male spontaneously hypertensive rats (SHRs) show an increased vascular neurogenic response compared with normotensive Wistar-Kyoto (WKY) control rats. OBJECTIVE To study the vascular adrenergic response in hypertensive and normotensive female rats, with a focus on the influence of oestrogen. METHODS Female SHRs and WKY rats were allocated randomly to a control group or to groups to undergo ovariectomy or ovariectomy combined with oestrogen supplementation (17beta-oestradiol 150 microg/kg per day) for either 1 day (group 1E2) or 10 days (group 10E2). Mean arterial pressure (MAP) was recorded and small mesenteric arteries were mounted in a Multi Myograph 610M. Vascular reactivities to transmural nerve stimulation (TNS), exogenous noradrenaline and acetylcholine were analysed. RESULTS MAP was significantly greater in SHRs than in WKY rats in all groups studied. Sensitivity to cumulative TNS (0.12-32 Hz) did not differ between vessels from control SHRs and WKY rats, expressed as the frequency giving 50% of maximal neurogenic response (Ef(50): 4.1 +/- 1.1 and 4.0 +/- 1.6 Hz, respectively). However, there was a greater reactivity to TNS in ovariectomized SHRs than in ovariectomized WKY rats (Ef(50) 1.8 +/- 0.7 and 6.8 +/- 2.2 Hz, respectively; P < 0.05). Oestradiol treatment significantly decreased the sensitivity to TNS in ovariectomized SHRs (P < 0.05), and after 10 days the frequency-response curves were almost identical (Ef(50) 6.3 +/- 1.9 Hz for group 10E2 SHRs and 5.6 +/- 0.8 Hz for group 10E2 WKY rats). The increased adrenergic reactivity in ovariectomized SHRs was inhibited by prazosin, an alpha(1)-adrenergic antagonist, and could not be explained by differences in endothelial function or sensitivity to applied noradrenaline. CONCLUSION Increased adrenergic reactivity is not present in small arteries from female SHRs. The findings of this study suggest that oestrogen acts on prejunctional mechanisms, reducing full expression of hypertension and peripheral vascular pathology.

OBJECTIVE The acute effects of estrogen on hemodynamic responses were studied with emphasis on the sympathoadrenal system and peripheral circulation. DESIGN Eleven healthy postmenopausal women recruited from the population-based study BEDA were included in this randomized, double-blind, cross-over, placebo-controlled hypothesis-generating pilot study, where the effect of transdermal estrogen (17 beta-estradiol, 100 microg/24 h) was tested. METHODS Twenty-four hours after the patch with estrogen/placebo was attached, the blood pressure during rest and mental stress test was measured, together with blood samples for analysis of P-adrenaline and P-noradrenaline. Twenty-four-hour ambulatory registration of blood pressure and heart rate were recorded. Contractile properties and endothelial function of subcutaneous small arteries from gluteal biopsies were studied with the wire-myograph technique. RESULTS Estrogen treatment reduced both ambulatory systolic blood pressure (5 mmHg, P = 0.05), diastolic blood pressure (3 mmHg, P < 0.05) and heart rate (6-8 beats/min during morning hours, P < 0.01). Diastolic blood pressure during and after mental stress was significantly reduced after estrogen treatment (p < 0.01). The levels of P-adrenaline and P-noradrenaline were similar in both treatment protocols. The contractile properties of the arteries were not significantly influenced by estrogen. Substance P induced nitric oxide-dependent relaxation in both estrogen-treated and placebo-treated precontracted arteries. Acetylcholine, on the other hand, induced a non-nitric oxide, non-prostanoid-dependent hyperpolarization, which was inhibited by potassium-induced depolarization after placebo but not after estrogen treatment. CONCLUSIONS Acute administration of transdermal estrogen in clinically relevant doses modulates hemodynamics, probably by an altered parasympathetic balance, which might involve changes at the muscarinic receptor level.

The aim of this study was to investigate the acute effects of transdermal 17β-estradiol (Estraderm®) on plasma levels of coagulatory and fibrinolytic factors in postmenopausal normotensive and hypertensive women. Eleven normotensive and 13 hypertensive women were included in this placebo-controlled crossover study. In a randomized order each subject was treated with a patch of 100 yig 17β-estradiol or placebo for 24 hours. Serum levels of tissue type plasminogen activator (tPA) activity, plasminogen activator inhibitor I (PAI-1) activity, tPA antigen, PAI-I antigen, FVII, FX, and fibrinogen were assayed after both treatments. There was no significant difference in serum levels of hemostatic variables after treatment with estrogen compared to levels after placebo treatment in either of the groups. Nor was there any measurable difference when comparing hypertensive and normotensive subjects.

The aim of the Evaluation-guided Development of New In Vitro Test Batteries (EDIT) multicentre programme is to establish and validate in vitro tests relevant to toxicokinetics and for organ-specific toxicity, to be incorporated into optimal test batteries for the estimation of human acute systemic toxicity. The scientific basis of EDIT is the good prediction of human acute toxicity obtained with three human cell line tests (R2 = 0.77), in the Multicentre Evaluation of In Vitro Cytotoxicity (MEIC) programme. However, the results from the MEIC study indicated that at least two other types of in vitro test ought to be added to the existing test battery to improve the prediction of human acute systemic toxicity — to determine key kinetic events (such as biotransformation and passage through biological barriers), and to predict crucial organ-specific mechanisms not covered by the tests in the MEIC battery. The EDIT programme will be a case-by-case project, but the establishment and validation of new tests will be carried through by a common, step-wise procedure. The Scientific Committee of the EDIT programme defines the need for a specific set of toxicity or toxicokinetic data. Laboratories are then invited to perform the defined tests in order to provide the “missing” data for the EDIT reference chemicals. The results obtained will be evaluated against the MEMO (the MEIC Monograph programme) database, i.e. against human acute systemic lethal and toxicity data. The aim of the round-table discussions at the 19th Scandinavian Society for Cell Toxicology (SSCT) workshop, held in Ringsted, Denmark on 6–9 September 2001, was to identify which tests are the most important for inclusion in the MEIC battery, i.e. which types of tests the EDIT programme should focus on. It was proposed that it is important to include in vitro methods for various kinetic events, such as biotransformation, absorption in the gut, passage across the blood–brain barrier, distribution volumes, protein binding, and renal clearance/accumulation. Models for target organ toxicity were also discussed. Because several of the outlier chemicals (paracetamol, digoxin, malathion, nicotine, paraquat, atropine and potassium cyanide) in the MEIC in vivo–in vitro evaluation have a neurotoxic potential, it was proposed that the development within the EDIT target organ programme should initially be focused on the nervous system.

OBJECTIVE: Growth hormone (GH) and oestrogen (E(2)) are associated with beneficial effects on the cardiovascular system and it is therefore of great interest to study their interactive effects on haemodynamics and vascular function. DESIGN AND METHODS: Female hypophysectomised (Hx) rats were treated for seven days with GH, E(2) or a combination of the hormones. Systolic blood pressure (SBP), heart rate (HR) and plasma insulin-like growth factor-I (IGF-I) were measured. Contractile properties and endothelial function were studied in isolated resistance arteries using the wire-myograph technique. RESULTS: Hypophysectomy, per se, caused a fall in SBP and HR, while vascular adrenergic reactivity (sensitivity to applied noradrenaline) was enhanced. Impaired acetylcholine-induced relaxation and basal release of nitric oxide, suggests endothelial dysfunction after Hx. After supplementation with GH, SBP remained low while HR increased towards the control level. GH increased plasma IGF-I, but had no effect on vascular contractility or endothelial responses. E(2) replacement resulted in blunted plasma IGF-I, while the vascular adrenergic and serotonergic responses were reinforced. Endothelial function was not improved after E(2) treatment. When GH and E(2) were given in combination, the GH-induced increase in body weight, plasma IGF-I levels and HR were counteracted by E(2). Moreover, the anticipated reinforcement of the vascular serotonergic response by E(2) was reduced. Neither E(2) nor GH+E(2) affected SBP. CONCLUSIONS: The results suggest that GH and E(2) might have interactive effects on haemodynamic and metabolic parameters, but not on the contractility or endothelial function of resistance arteries, in Hx female rats.

To evaluate maximal isometric muscle force at 18 years of age in relation to Parkinson disease (PD) later in life.The cohort consisted of 1,317,713 men who had their muscle strength measured during conscription (1969-1996). Associations between participants' muscle strength at conscription and PD diagnoses, also in their parents, were examined using multivariate statistical models.After adjustment for confounders, the lowest compared to the highest fifth of handgrip strength (hazard ratio [HR] 1.38, 95% confidence interval [CI] 1.06-1.79), elbow flexion strength (HR 1.34, 95% CI 1.02-1.76), but not knee extension strength (HR 1.24, 95% CI 0.94-1.62) was associated with an increased risk of PD during follow-up. Furthermore, men whose parents were diagnosed with PD had reduced handgrip (fathers: mean difference [MD] -5.7 N [95% CI -7.3 to -4.0]; mothers: MD -5.0 N [95% CI -7.0 to -2.9]) and elbow flexion (fathers: MD -4.3 N [95% CI -5.7 to -2.9]; mothers: MD -3.9 N [95% CI -5.7 to -2.2]) strength, but not knee extension strength (fathers: MD -1.1 N [95% CI -2.9 to 0.8]; mothers: MD -0.7 N [95% CI -3.1 to 1.6]), than those with no such familial history.Maximal upper extremity voluntary muscle force was reduced in late adolescence in men diagnosed with PD 30 years later. The findings suggest the presence of subclinical motor deficits 3 decades before the clinical onset of PD.

The bestrophin isoform, bestrophin-3 (Best3), acts as a calcium-activated chloride channel in cardiomyocytes and in vascular smooth muscle. It may have cell-protective functions in other cell types...

PurposeThe purpose of this paper is to compare the implementation of 12 different organisation and management innovations (OMIs) in Swedish healthcare, to discover the generic and specific factors important for successful healthcare improvement change in a public health system.Design/methodology/approachLongitudinal cross‐case comparison of 12 case studies was employed, where each case study used a common framework for collecting data about the process of change, the content of the change, the context, and the intermediate and final outcomes.FindingsClinical leaders played a more important part in the development of these successful service innovations than managers. Strategies for and patterns of change implementation were found to differ according to the type of innovation. Internal organisational context factors played a significant role in the development of nearly all, but external factors did not. “Developmental evolution” better described the change process than “implementation”.Research limitations/implicationsThe 12 cases were all of relatively successful change processes: some unsuccessful examples would have provided additional testing of the hypotheses about what would predict successful innovation which were used in the case comparison. The cross‐case comparative hypothesis testing method allows systematic comparison if the case data are collected using similar frameworks, but this approach to management research requires considerable resources and coordination.Practical implicationsManagement innovations that improve patient care can be carried out successfully by senior clinicians, under certain circumstances. A systematic approach is important both for developing and adapting an innovation to a changing situation. A significant amount of time was required for all involved, which could be reduced by “fast‐tracking” approval for some types of change.Originality/valueThis is the first empirical report comparing longitudinal and contextualised findings from a number of case studies of different organisational and management healthcare innovations. The findings made possible explanations for success factors and useful practical recommendations for conditions needed to nurture such innovation in public healthcare.

Background Radiotherapy (RT) units are high-tech nursing environments. In Sweden, RT registered nurses (RNs) provide and manage RT in close collaboration with other professional groups, as well as providing nursing care for patients with cancer. Communication demands on these RNs are thus particularly complex. In this study, we aimed to better understand problems, strengths and change needs related to professional communication with and within the RT department, as a basis for developing a situation-specific intervention. Methods Focus groups discussions (FGDs) were conducted with different professional (RNs, assistant nurses, physicians, engineers and physicists) and user stakeholders. Transcripts of the FGDs were inductively analyzed by a team of researchers, to generate clinically relevant and useful data. Results These findings give insight into RT safety climate and are presented under three major headings: Conceptualization of professional domains; Organization and leadership issues; and Communication forms, strategies and processes. The impact of existing hierarchies, including how they are conceptualized and acted out in practice, was noted throughout these data. Despite other differences, participating professionals agreed about communication problems related to RT, i.e. a lack of systems and processes for information transfer, unclear role differentiation, a sense of mutual disrespect, and ad hoc communication taking place ‘on the fly’. While all professional groups recognized extensive communication problems, none acknowledged the potential negative effects on patient safety or care described in the FGD with patient representatives. While RNs often initially denied the existence of a hierarchy, they placed themselves on a hierarchy in their descriptions, describing their own role as passive, with a sense of powerlessness. Potential safety hazards described in the FGDs include not reporting medical errors and silently ignoring or actively opposing new guidelines and regulations. Conclusions There is a risk that RNs who view themselves as disenfranchised within an organization will act with passive resistance to change, rather than as change promoters. As interventions to strengthen teams cannot be stronger than the weakest link, RNs may need support in the transition “from silence to voice” in order to take a position of full professional responsibility in a multi-professional health care team.

Small mesenteric arteries from Wistar rats display rhythmic tension oscillations, associated with oscillations in membrane potential, when stimulated with noradrenaline. The purpose of this study was to investigate the role of potassium conductance and Na+, K(+)-pump activity in the generation of these oscillations. The effect on the rhythmic contractions of several agents, interacting with K+ channels, was studied. Application of apamin, pinacidil or glibenclamide did not affect the rhythmic activity. Tetraethylammonium (TEA) increased the frequency of the rhythmic contractions, while application of 4-aminopyridine (4-AP) increased the amplitude by approximately 50%, with no changes in frequency. Ba2+, on the other hand, impaired the rhythmic contractions or converted them to irregular oscillations in the presence of functional endothelium, but did not affect oscillations in endothelium-denuded vessels. Ouabain or exposure to K(+)-free solution, procedures known to inhibit the Na+,K(+)-pump, abolished the rhythmic contractions. This effect was immediate, suggesting that it was due to elimination of the electrogenic action of the Na+,K(+)-ATPase, rather than to a change in intracellular ion concentrations. Exposure to an extracellular potassium concentration of more than 20 mM also inhibited the oscillation activity. The results suggest that the oscillations are not caused by, but may be modulated by, variations in potassium conductance. The Na+,K(+)-pump seems to play an important role in the generation of rhythmic contractions in these vessels.

In order to investigate the mechanisms behind rhythmic contractions in small arteries of the mesenteric arcade from Wistar rats, the calcium dependency of the oscillations in response to noradrenaline activation was tested on isolated vessels. Application of 1 microM ryanodine or 30 microM TMB-8 (procedures known to inhibit Ca2+ release from intracellular stores) totally abolished the rhythmic activity, even though the antagonists had opposite effects on the amplitude of the contractile response to noradrenaline. Verapamil (1 microM) or felodipine (1 nM) (agents known to inhibit influx of extracellular Ca2+) also abolished the oscillations and reduced the maximal noradrenaline response by about 40%. Reducing the extracellular Ca2+ concentration to 0.1 mM reduced the amplitude of the noradrenaline response to a similar extent as 1 nM felodipine, but did not eliminate the oscillations. This may indicate that the effect of calcium entry blockers was to eliminate the voltage-dependency of Ca2+ inflow rather than just reducing the Ca2+ level. Manoeuvres that would increase the cytosolic Ca2+ concentration (exposure to caffeine or to the calcium agonist BAY-K 8644) increased the frequency of the oscillations. These observations indicate an important role, not only for voltage-operating channels, but also for intracellular calcium stores in the generation of rhythmic contractions in these small arteries. Oscillations appear to be generated by an interplay between membrane activation and intracellular calcium stores.

The aim of this investigation was to study the effects of hormone replacement therapy (HRT) on left ventricular mass (LVM) and serum-angiotensin-converting enzyme (ACE) activity (S-ACE) in well controlled hypertensive postmenopausal women.In this prospective, randomized, crossover, double-blind trial we studied 20 well controlled hypertensive postmenopausal women who received 6 months of HRT and 6 months of placebo on top of antihypertensive treatment. Two-dimensional M-mode, office blood pressure, 24-h ambulatory blood pressure (ABPM), S-estradiol and S-ACE activity were investigated at baseline, after 6 and 12 months.LVM was significantly influenced by HRT (analysis of variance, ANOVA, p0.01). However, the order in randomization of HRT and placebo had an impact on the analysis of LVM reduction (baseline - HRT - placebo: ns; baseline - placebo - HRT: p0.01 ANOVA). Only the women lacking blockade of the renin-angiotensin-aldosterone system (RAAS) as antihypertensive treatment (n=10) experienced a reduction in LVM and a tendency of decreased S-ACE activity in response to HRT compared with baseline (p0.05 and p= 0.06 respectively).Six months of HRT resulted in significant reduction of LVM without any change in ABPM. HRT may reduce LVM through interaction with the RAAS, since hypertensive women without RAAS blockade exhibited an effect of HRT on LVM and S-ACE activity, which was not seen in women on RAAS blockade.

To investigate the medium-term effects of estrogen plus progesterone therapy (EPT) on vascular reactivity, endothelial function and hemodynamic responses in 20 hypertensive postmenopausal women.This randomized, double-blind, cross-over, placebo-controlled study investigates the effect of 6 months of EPT (conjugated equine estrogen plus medroxyprogesterone). Blood pressure (office and ambulatory), heart rate and heart rate variability (HRV) were measured at baseline and following EPT/placebo treatment. In eight women, we used a wire-myograph to assess endothelial function and contractile response of subcutaneous arteries to transmural nerve stimulation (TNS) and exogenous noradrenaline.EPT decreased vascular reactivity to cumulative TNS compared with baseline (p0.01) and placebo (p0.05). Moreover, EPT diminished sensitivity to exogenous noradrenaline (p0.05). Although EPT reinforced response to acetylcholine, we observed no difference in maximal relaxation induced by substance P or acetylcholine. EPT did not affect ambulatory blood pressure, heart rate or HRV.Oral combined medium-term EPT reduces adrenergic reactivity in subcutaneous arteries from treated hypertensive postmenopausal women. EPT might act postjunctionally at the adrenergic vascular receptor level. In the present study, EPT neither reduces sympathetic activity nor increases vagal tone, and thus does not support an effect on the central hemodynamic system.

The objective of the EU-funded integrated project ACuteTox is to develop a strategy in which general cytotoxicity, together with organ-specific toxicity and biokinetic features, are used for the estimation of human acute systemic toxicity. Our role in the project is to characterise the effect of reference chemicals with regard to neurotoxicity. We studied cell membrane potential (CMP), noradrenalin (NA) uptake, acetylcholine esterase (AChE) activity, acetylcholine receptor (AChR) signalling and voltage-operated calcium channel (VOCC) function in human neuroblastoma SH-SY5Y cells after exposure to 23 pharmaceuticals, pesticides or industrial chemicals. Neurotoxic alert chemicals were identified by comparing the obtained data with cytotoxicity data from the neutral red uptake assay in 3T3 mouse fibroblasts. Furthermore, neurotoxic concentrations were correlated with estimated human lethal blood concentrations (LC50). The CMP assay was the most sensitive assay, identifying eight chemicals as neurotoxic alerts and improving the LC50 correlation for nicotine, lindane, atropine and methadone. The NA uptake assay identified five neurotoxic alert chemicals and improved the LC50 correlation for atropine, diazepam, verapamil and methadone. The AChE, AChR and VOCC assays showed limited potential for detection of acute toxicity. The CMP assay was further evaluated by testing 36 additional reference chemicals. Five neurotoxic alert chemicals were generated and orphendrine and amitriptyline showed improved LC50 correlation. Due to the high sensitivity and the simplicity of the test protocol, the CMP assay constitutes a good candidate assay to be included in an in vitro test strategy for prediction of acute systemic toxicity.

To compare the dose-response relationships of two formulations [Tween- or hydroxypropyl-b-cyclodextrin (HP-b-CD)-based] of intradermal capsaicin in healthy volunteers and to assess the effect of potential covariates of response. One, 10, 30 and 100 microg in 10 ml were compared for the outcomes of flare, spontaneous pain, mechanical allodynia and hyperalgesia in eight healthy men and eight healthy women.The formulations produced comparable responses at doses 1, 10 and 30 microg, but in all parameters the response was less at 100 microg with the Tween formulation.Mean area for hyperalgesia was 9 cm(2) [95% confidence interval (CI) 5, 13] higher with the HP-beta-CD formulation. Flare area was 5 cm(2) (95% CI 8, 13) greater with the HP-beta-CD formulation. There was a significant difference between pain responses from the injection site on the upper forearm compared with the lower forearm on all four pain assessments. In contrast, significant differences were seen in pain response between nondominant and dominant arm for flare, allodynia and hyperalgesia but not for spontaneous pain. A significant difference in sex was seen only for hyperalgesia. The nominal 100-microg dose of the Tween formulation contained only 39% of label strength in the aqueous phase, which may explain the lower pharmacodynamic response.The formulations are comparable over the dose range 1-30 microg. The significantly lower pain response at the 100 microg dose in the Tween compared with the HP-beta-CD formulation is likely to be due to limitations in solubility at the 100 microg level. Given the greater ease of formulation and the superior dose-response relationship, the HP-beta-CD formulation is preferable for use in the model in future studies.

et al., The objective of the EU funded integrated project “ACuteTox” is to develop a strategy in which general cytotoxicity, together with organ-specific endpoints and biokinetic features, are taken into consideration in the in vitro prediction of oral acute systemic toxicity. With regard to the nervous system, the effects of 23 reference chemicals were tested with approximately 50 endpoints, using a neuronal cell line, primary neuronal cell cultures, brain slices and aggregated brain cell cultures. Comparison of the in vitro neurotoxicity data with general cytotoxicity data generated in a non-neuronal cell line and with in vivo data such as acute human lethal blood concentration, revealed that GABAA receptor function, acetylcholine esterase activity, cell membrane potential, glucose uptake, total RNA expression and altered gene expression of NF-H, GFAP, MBP, HSP32 and caspase-3 were the best endpoints to use for further testing with 36 additional chemicals. The results of the second analysis showed that no single neuronal endpoint could give a perfect improvement in the in vitro–in vivo correlation, indicating that several specific endpoints need to be analysed and combined with biokinetic data to obtain the best correlation with in vivo acute toxicity., The project was financed by the EU-FP6 Grant (FP6-LIFESCIHEALTH-2004-512051, the Swedish Animal Welfare Agency, the Swedish Fund for Research without Animal Experiments, Spain’s Ministerio de Educación y Ciencia (SAF2005-01604, SAF2006-13092) and the Spanish PI061212 project from Ministry of Health.

Uncoupling proteins (UCPs) have been reported to decrease the mitochondrial production of reactive oxygen species (ROS) by lowering the mitochondrial inner membrane potential (MMP). We have previously shown that UCP3 expression is positively regulated by insulin-like growth factor-1 (IGF-1). The aim of this study was to investigate the role of UCPs in IGF-1-mediated protection from hyperglycemia-induced oxidative stress and neurodegeneration. Human neuroblastoma SH-SY5Y cells were differentiated with retinoic acid for 6 days, after which exposure to 8, 30, or 60 mM glucose with or without 10 nM IGF-1 was started. After 48-72 hr, the number of neurites per cell, UCP3 protein expression, MMP, and intracellular levels of ROS and total glutathione were examined. These studies showed that glucose concentration-dependently reduced the number of neurites per cell, with a 50% reduction at 60 mM. In parallel, the UCP3 protein expression was down-regulated, and the MMP was raised 3.5-fold, compared with those in cells incubated with 8 mM glucose. Also, the ROS levels were increased, showing a twofold maximum at 60 mM glucose. This was accompanied by a twofold elevation of total glutathione levels, confirming an altered cellular redox state. IGF-1 treatment prevented the glucose-induced neurite degeneration and UCP3 down-regulation. Furthermore, the MMP and the intracellular levels of ROS and glutathione were normalized to those of control cells. These data indicate that IGF-1 may protect from hyperglycemia-induced oxidative stress and neuronal injuries by regulating MMP, possibly by the involvement of UCP3.

Uncoupling protein 3 (UCP3) is a mitochondrial protein with antioxidant properties and its regulation by factors promoting cell-survival may be important for protection of, for instance, neurons in states of oxidative stress. In the present study, we investigated regulatory pathways for UCP3 expression mediated by the neuroprotective hormone insulin-like growth factor type 1 (IGF-1) in human neuroblastoma SH-SY5Y cells. Northern blot analysis and RT-PCR showed that treatment with 10 nm IGF-1 increased the UCP3 mRNA levels 2.5-fold after 5 h. Co-incubation with the phosphatidylinositol 3 (PI3)-kinase inhibitor LY294002 prohibited IGF-1-mediated induction of both UCP3 mRNA and protein in a concentration-dependent manner, with a complete blockage at 1 microm, as shown by RT-PCR and western blot analyses. The mitogen-activated protein (MAP) kinase kinase 1 (MKK1 or MEK) inhibitor PD98059 also decreased the UCP3 mRNA expression at 10 microm, however, this concentration only partly inhibited the protein expression. We conclude that IGF-1 enhanced UCP3 expression at transcriptional level, primarily through the PI3-kinase-dependent pathway and partly through the MAP kinase pathway.

The aim of the Evaluation-guided Development of new In Vitro Test Batteries (EDIT) multicentre programme is to establish and validate in vitro tests relevant to toxicokinetics and for organ-specific toxicity, to be incorporated into optimal test batteries for the estimation of human acute systemic toxicity. The scientific basis of EDIT is the good prediction of human acute toxicity obtained with three human cell line tests (R(2) = 0.77), in the Multicentre Evaluation of In Vitro Cytotoxicity (MEIC) programme. However, the results from the MEIC study indicated that at least two other types of in vitro test ought to be added to the existing test battery to improve the prediction of human acute systemic toxicity - to determine key kinetic events (such as biotransformation and passage through biological barriers), and to predict crucial organ-specific mechanisms not covered by the tests in the MEIC battery. The EDIT programme will be a case-by-case project, but the establishment and validation of new tests will be carried through by a common, step-wise procedure. The Scientific Committee of the EDIT programme defines the need for a specific set of toxicity or toxicokinetic data. Laboratories are then invited to perform the defined tests in order to provide the "missing" data for the EDIT reference chemicals. The results obtained will be evaluated against the MEMO (the MEIC Monograph programme) database, i.e. against human acute systemic lethal and toxicity data. The aim of the round-table discussions at the 19th Scandinavian Society for Cell Toxicology (SSCT) workshop, held in Ringsted, Denmark on 6-9 September 2001, was to identify which tests are the most important for inclusion in the MEIC battery, i.e. which types of tests the EDIT programme should focus on. It was proposed that it is important to include in vitro methods for various kinetic events, such as biotransformation, absorption in the gut, passage across the blood-brain barrier, distribution volumes, protein binding, and renal clearance/accumulation. Models for target organ toxicity were also discussed. Because several of the outlier chemicals (paracetamol, digoxin, malathion, nicotine, paraquat, atropine and potassium cyanide) in the MEIC in vivo-in vitro evaluation have a neurotoxic potential, it was proposed that the development within the EDIT target organ programme should initially be focused on the nervous system.

In this study the expression of uncoupling protein 3 (UCP3) and its regulation by insulin-like growth factor 1 (IGF-I) and insulin in human neuroblastoma SH-SY5Y cells were characterized. Reverse transcriptase-PCR, Western blot, and immunofluorescence analysis showed that SH-SY5Y cells express UCP3 natively. IGF-I induced a time- and concentration-dependent induction of UCP3 protein reaching a twofold expression after 72 h with 10 nM IGF-I. Extremely high insulin concentrations (860 nM) and 10 nM trIGF-I, a truncated form of IGF-I with the same affinity for the IGF-I receptor as the full-length IGF-I, but with lower activity on the insulin receptor, also upregulated UCP3. We conclude that SH-SY5Y cells express UCP3 natively and that the expression is regulated by IGF-I via the IGF-I receptor.

Acromegaly is associated with cardiovascular disease. We studied vascular function and mean arterial blood pressure in transgenic mice overexpressing bovine GH. Mean arterial blood pressure was measured in conscious, unrestrained male and female bovine GH and littermate control mice during normal as well as high salt intake using telemetric devices. Structure in artificially perfused maximally dilated hindquarter vascular beds and vascular reactivity and endothelial function in small mesenteric vessels were studied in female bovine GH and control mice. Mean arterial blood pressure was increased in female bovine GH transgenic (126 +/- 3 mm Hg) and male bovine GH transgenic (129 +/- 4 mm Hg) compared with female (109 +/- 3 mm Hg, P < 0.05) and male (111 +/- 3 mm Hg, P < 0.05) controls respectively. Increased salt intake had no effect on mean arterial blood pressure. Perfusion studies showed a significant decrease in the average diameter of the female bovine GH transgenic hindquarter vascular bed (P < 0.05). The responses of isolated resistance arteries to nor-epinephrine, potassium-induced depolarization, acetylcholine, or sodium-nitroprusside did not significantly differ between bovine GH transgenic and control mice. We conclude that the phenotype of the bovine GH transgenic mice includes a salt-resistant form of hypertension. Furthermore, the increase in mean arterial blood pressure is accompanied by a significant structural narrowing of the resistance vasculature without changes in vascular reactivity or endothelial function. The results imply that hypertension in bovine GH transgenic mice is maintained mainly by a structurally based increase in peripheral vascular resistance.

The present study was undertaken to examine the influence of transmural pressure on vasomotion and to determine if any such influence was endothelium–dependent. Responses to changes in intravascular pressure of cannulated mesenteric small arteries were investigated under no–flow conditions. Both intact and endothelium–denuded arteries dilated passively when intravascular pressure was increased stepwise from 20 to 140 mmHg. When tone was induced by noradrenaline, pressure increase resulted only in dilatation, independent of endothelium. The sensitivity to noradrenaline was significantly increased in vessels without endothelium, indicating a relaxing influence of the endothelium. Rhythmic contractions in response to noradrenaline occurred in all intact arteries, but were absent when the endothelium was removed. The amplitude of the rhythmic contractions decreased significantly when transmural pressure was elevated. The frequency increased when pressure was elevated from 20 to 80 mmHg and then remained rather constant during further pressure increases. As shown previously in non–pressurized arteries, exogenous cyclic GMP induced oscillations in endothelium–denuded arteries. Pressure–related effects on vasomotion were not dependent on an intact endothelium. Ryanodine, ouabain or verapamil inhibited the rhythmic activity, confirming previous results in non–pressurized arteries. Thus, changes in transmural pressure can modulate vasomotion, but this effect does not appear to be mediated by the endothelium. Generation of vasomotion may depend on release of Ca2+ from intracellular stores, the activity of the Na+, K+–pump and transmembrane Ca2+ inflow in a pressurized artery as shown previously in these arteries under isometric conditions.

Small arteries of the mesenteric arcade from Wistar rats display rhythmic oscillations superimposed on the tonic contractile response when exposed to submaximal doses of noradrenaline. We have previously shown that mechanical removal of the endothelium abolishes these oscillations. In the present study different methods to eliminate or modify the influence of the endothelium were used in order to further characterize the mechanisms behind rhythmic contractions in these vessels. Endothelium was removed either mechanically or chemically by perfusing the vessels with 0.3% CHAPS. The absence of functional endothelium enhanced noradrenaline sensitivity and simultaneously abolished oscillations in tension and membrane potential, but did not affect resting membrane potential. The rhythmic activity was also reduced or abolished by exposure to haemoglobin, methylene blue, LY83583 or L-NNA. Indomethacin and propranolol were without effect. Sodium nitroprusside or the permeant analogue of cyclic GMP, 8-bromo cyclic GMP, restored rhythmic activity in precontracted endothelium-denuded vessels. The data suggest that release of nitric oxide from the endothelium, and subsequent generation of cyclic GMP in the smooth muscle, activates oscillations in membrane potential and tension; the oscillator itself appears to be located within the smooth muscle cells.

The circulatory effects of morphine abstinence have recently been found to involve decreased renal sympathetic nerve activity and increased mean arterial pressure, induced by vasoconstriction. A direct influence of morphine withdrawal on the peripheral vasculature could possibly contribute to the increased resistance. Therefore, contractile responses to transmural nerve stimulation and to applied noradrenaline of peripheral arteries from morphine-dependent and untreated rats were examined in vitro under paired conditions. No increase in contractile response was observed after chronic morphine treatment, either on nerve stimulation or on applied noradrenaline. Instead the smooth muscle sensitivity to adrenergic stimulation was reduced. Consequently, the present study does not support a peripheral adrenergic origin of the vasoconstriction during naloxone-precipitated morphine abstinence.

An endothelium-dependent action of neuropeptide Y (NPY) has been implicated in studies on various vascular beds. In the present study, the requirement of an intact endothelium for NPY-evoked potentiation of the response to sympathetic nerve stimulation was determined in the small mesenteric arteries of the rat and in the central ear artery of the rabbit. Further, NPY-mediated inhibition of relaxing influences was determined in small mesenteric arteries of the rat. Vascular segments were mounted in a double myograph, where one of the two suspended vessels was denuded of endothelium by gently rubbing the intimal surface. Removal of endothelium was verified by en-face silver staining. In both species, the response to bursts of transmural field stimulation eliciting 10% of maximal contraction was potentiated 2-4 times in the presence of 10 nM NPY, whether the endothelium was present or not. In small mesenteric arteries precontracted with noradrenaline, addition of acetylcholine (I microM) caused relaxation only in vessels with an intact endothelium. Subsequent addition of 10 nM NPY enhanced vasoconstriction in both intact and endothelium-denuded vessels. The endothelium-independent beta-adrenergic agonist isoprenaline (I microM) relaxed both intact and denuded small mesenteric arteries, and in both further addition of 10 nM NPY increased the contraction to about the same extent. The results demonstrate that NPY potentiates the responses to sympathetic field stimulation in small mesenteric arteries from the rat and in central ear artery from rabbit whether the endothelium is present or not. NPY inhibits both endothelium-dependent and -independent relaxations in small mesenteric arteries from rat.

We have studied the neurogenic response of small mesenteric arteries from the rat to evaluate the involvement of possible co-transmitters under various modes of stimulation. Segments of small branches of the mesenteric artery were mounted in a myograph and the intramural nerves were activated with transmural electrical stimulation. A single stimulation of the nerves caused a contraction that was reduced by only 20% in the presence of adrenergic blocking agents (prazosin or phenoxybenzamine), whereas the steady-state response to continuous nerve stimulation of high frequency was reduced by 90–95 %. In contrast, all responses to applied noradrenaline in doses up to at least 1 mM were eliminated by phenoxybenzamine treatment. The stable ATP analogue, α,β-methylene ATP, reduced the response to a single nerve stimulation by 70%, but reduced the contraction caused by continuous high-frequency nerve stimulation by only 10%. None of these agents affected the response to applied neuropeptide Y (NPY). The response of relaxed vessels to nerve stimulation was totally blocked by the combination of an adrenoceptor-blocking agent and α,β-methylene ATP, although even in this situation a further neurogenic response could be revealed in vessels precontracted with vasopressin. Responses to either single stimuli or brief burst stimulations were potentiated after high-frequency stimulation. Both the adrenergic and non-adrenergic components were enhanced to roughly the same extent. Also the potentiated response was eliminated by the combined application of prazosin and α,β-methylene ATP. The non-adrenergic transmitter in the sympathetic nerves of small arteries thus appears to be the dominant transmitter during low-frequency nerve stimulation, causing rapid but phasic activation. Noradrenaline is the most important transmitter for higher frequencies, exerting slower but sustained contractions. The post-stimulatory potentiation affects both the adrenergic and the non-adrenergic part of the neurogenic response.

Diabetic neuropathy may be induced by oxidative stress, possibly as a consequence of the hyperglycemic situation. Uncoupling proteins (UCPs) have been reported to function as anti-oxidants by decreasing the production of reactive oxygen species (ROS). These mitochondrial carrier proteins are located in the inner membrane of mitochondria and upon activation, they dissipate proton gradients, which generates heat instead of ATP. In humans, UCP2 and UCP3 are believed to play a role as energy dissipaters and aberrant function could underlie metabolic defects seen in both obesity and non-insulin dependent diabetes (NIDDM). In this study we have shown that human neuroblastoma SH-SY5Y cells expressed UCP2 and UCP3 natively and that the expression was upregulated by insulin and IGF-I via the IGF-I receptor. In highly differentiated SH-SY5Y cells, which were cultured in hyperglycemic N2-medium (30 mM and 60 mM glucose) containing 8.6 nM insulin, the number of neurites per cell and total cellular protein levels/dish were significantly decreased, as compared to cells grown in N2-medium containing 17 mM glucose. This effect was abolished when the cells were grown with 10 nM IGF-I at 30 mM glucose and decreased at 60 mM glucose. Furthermore, in hyperglycemic cells, the IGF-I-induced increase in UCP3 protein levels was inhibited. Non-differentiated cells responded to hyperglycemic situations by increased rate of proliferation, leaving cell morphology intact. We conclude that differentiated SH-SY5Y cells can serve as an in vitro model for hyperglycemic neurons and that IGF-I protects the cells from hyperglycemia-induced neuropathy, suggestively by the involvement of UCP3.

Various in-vitro studies have indicated a direct attenuating effect of sodium on the affinity of adrenergic alpha 2-receptors. It has been suggested that ingested sodium in this way might increase blood pressure by reducing the activity of central alpha 2-receptors and thereby increasing sympathetic discharge. However, such an effect of sodium would also impair the function of peripheral alpha 2-receptors. In the present study we have therefore investigated the effect of high sodium intake on the alpha 2-receptor-mediated inhibition of the vascular neurogenic response. Male Wistar rats were given 2% NaCl in their drinking water from 4 to 9 weeks of age. Another group receiving plain tap water served as controls. Segments of small branches from the mesenteric artery were mounted in a myograph. Responses to transmural nerve stimulation were determined before and after alpha 2-receptor blockade with either yohimbine or idazoxan. The response to a continuous nerve stimulation that elicited 30% of maximal contraction was increased 2-3 times after addition of either idazoxan (0.1 microM) or yohimbine (0.3 microM), with no significant difference between sodium-treated and control rats; if anything the enhancement was slightly greater in the sodium-treated group. Also, responses to intermittent burst stimulation were increased from 30 to about 80% of maximal response in both rat groups. The results thus indicate that high sodium intake does not affect the inhibitory influence of pre-junctional alpha 2-receptors on the vascular neurogenic response.

Aim Bestrophins are putative calcium-activated chloride channels. Recently, cell-protective functions for Bestrophin-3 (Best3) were proposed. Best3 exists in different splice variants. We have here examined expression, alternative splicing and localization of Best3 in mouse podocytes under normal conditions and during endoplasmic reticulum (ER) stress. Methods Best3 expression was determined on the mRNA level using quantitative PCR and on the protein level by immunohistochemistry and Western blotting. Results Staining for Best3 was pronounced in glomeruli and was detected in cultured mouse podocytes. Best3 did not co-localize with markers for endothelial cells (CD31), podocyte foot processes (synaptopodin) or microtubules (actin). However, immunogold-based electron microscopy and co-localization with nestin showed Best3 presence in podocyte primary processes and cell bodies. Only two splice variants of Best3 mRNA (both lacking exons 2 and 3, and one also lacking exon 6), but no full-length variant, were detected. ER stress induced by lipopolysaccharides in vivo transiently elevated mRNA levels of total Best3 and its two splice variants with different time courses. In cultured podocytes under ER stress induced by thapsigargin, the expression of total Best3, its splice variants and nestin transiently increased with similar time courses. The ER stress marker C/EBP homologous protein (CHOP) and nestin mRNA increased during ER stress in vivo and in vitro. Conclusions Best3 is localized intracellularly in cell bodies and primary processes of mouse podocytes and is co-localized with nestin. Two splice variants of Best3 are expressed in glomeruli and in cultured podocytes, and their expression is differentially regulated in ER stress.

Ouabain, a specific inhibitor of the Na + /K + -pump, has previously been shown to interfere with intercellular communication. Here we test the hypothesis that the communication between vascular smooth muscle cells is regulated through an interaction between the Na + /K + -pump and the Na + /Ca 2+ -exchanger leading to an increase in the intracellular calcium concentration ([Ca 2+ ] i ) in discrete areas near the plasma membrane. [Ca 2+ ] i in smooth muscle cells was imaged in cultured rat aortic smooth muscle cell pairs (A7r5) and in rat mesenteric small artery segments simultaneously with force. In A7r5 coupling between cells was estimated by measuring membrane capacitance. Smooth muscle cells were uncoupled when the Na + /K + -pump was inhibited either by a low concentration of ouabain, which also caused a localized increase of [Ca 2+ ] i near the membrane, or by ATP depletion. Reduction of Na + /K + -pump activity by removal of extracellular potassium ([K + ] o ) also uncoupled cells, but only after inhibition of K ATP channels. Inhibition of the Na + /Ca 2+ -exchange activity by SEA0400 or by a reduction of the equilibrium potential (making it more negative) also uncoupled the cells. Depletion of intracellular Na + and clamping of [Ca 2+ ] i at low concentrations prevented the uncoupling. The experiments suggest that the Na + /K + -pump may affect gap junction conductivity via localized changes in [Ca 2+ ] i through modulation of Na + /Ca 2+ -exchanger activity.