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Epidemiological and clinical studies have demonstrated that excessive salt intake causes severe hypertension and exacerbates organ derangement, such as in chronic kidney disease (CKD). In this study, we focused on evaluating the histological and gene expression effects in the kidneys of stroke-prone spontaneously hypertensive rats (SHRSP) with a high salt intake and the thromboxane A2 / prostaglandin H2 receptor (TPR) blocker ONO-8809. Six-week-old SHRSPs were divided into three groups and were fed normal chow containing 0.4% NaCl, 2.0%NaCl or 2.0%NaCl + ONO-8809 (0.6 mg/kg p.o. daily). Histological analyses with immunohistochemistry and a gene expression assay with a DNA kidney microarray were performed after 8 weeks. The following changes were observed in SHRSPs with the high salt intake. Glomerular sclerotic changes were remarkably observed in the juxtamedullary cortex areas. The ED1, monocyte chemoattractant protein-1 (MCP-1), nitrotyrosine and hypoxia inducible factor 1α (HIF-1α) staining areas were increased in the glomeruli and interstitial portion of the kidneys. The genes Tbxa2r (that encodes TPR), Prcp and Car7 were significantly underexpressed in the kidneys. The plasma 8-isoprostane level was significantly elevated and was attenuated with the ONO-8809 treatment. Thromboxane A2 (TXA2 ) and oxidative stress exaggerated renal dysfunction in the salt-loaded SHRSPs, and ONO-8809 as a TPR blocker suppressed these changes. Therefore, ONO-8809 is a candidate drug to prevent CKD in hypertensive patients when CKD is associated with a high salt intake.

Non-technical summary Elevated blood glucose is generally regarded as one of the risk factors that lead to coronary heart disease in patients with type 2 diabetes. However, our studies show that after inducing short-term damage, high blood glucose subsequently provides paradoxical protection for vessel function of animals with high blood pressure. Vessels can adapt to sustained high blood glucose and produce different stress proteins to counteract, to some extent, the damage brought about by hypertension. The results help us understand part of the basis for vessel adaptation in diabetes. The implication for treatment of diabetes is that if the patients have long-standing diabetes and established cardiovascular disease, the target of blood glucose lowering should be less stringent and reached gradually to avoid abrupt cancellation of the pre-existing adaptations., Although both diabetes and hypertension are risk factors for cardiovascular disease, the role of hyperglycaemia per se in endothelial dysfunction is controversial. This study was designed to examine whether hyperglycaemia, or streptozotocin-induced diabetes, could aggravate endothelial dysfunction in stroke-prone spontaneously hypertensive rats (SHRSP). Hyperglycaemia was induced by streptozotocin in 2-month-old SHRSP and age-matched normotensive Wistar–Kyoto (WKY) rats. The aorta was isolated 8 weeks after induction of hyperglycaemia to record its function and to examine its morphology with transmission electron microscopy. Endothelial/inducible nitric oxide synthase (eNOS/iNOS) and inducible/constitutive haem oxygenase (HO-1/HO-2) levels were determined with Western blotting. Aortic endothelial function and production of reactive oxygen species and nitric oxide were assayed after incubation in vitro in hyperglycaemic, hyperosmolar solution. Streptozotocin-induced diabetes of 8 weeks duration did not result in endothelial dysfunction in normotensive WKY rats. In contrast, hyperglycaemic WKY rats showed significantly enhanced endothelium-dependent vasodilatation, which was abrogated by simultaneous blocking of NOS and HO. The enhanced vasodilatation was associated with elevation of vascular eNOS and HO-1. Significant endothelial dysfunction and massive macrophage–monocyte infiltration were found in SHRSP aorta (the ratio of the number of macrophages to endothelial cells in the intima, expressed as a percentage, was 20.9 ± 2.8% in SHRSP versus 1.9 ± 0.5% in WKY rats, P < 0.01), which was attenuated significantly in hyperglycaemic SHRSP (11.3 ± 1.6%, P < 0.01 versus SHRSP). Acute hyperglycaemia (10 min) aggravated endothelial dysfunction in SHRSP, with a marked increase in intracellular reactive oxygen species and NO production. Sustained in vitro incubation in hyperglycaemic/hyperosmolar conditions (addition of an extra 50 mmol L−1 of glucose or mannitol to the usual buffer, to produce a final osmolarity of 350 mosmol L−1) for 5 h enhanced endothelium-dependent vasodilatation, with elevated vessel NO production and upregulation of eNOS/HO-1 proteins. Sustained hyperglycaemia does not aggravate endothelial dysfunction and macrophage infiltration in SHRSP. Hyperglycaemia/hyperosmolarity-induced upregulation of eNOS and HO-1 may play a role in this paradoxical adaptation of endothelial function.

Systemic carbamazepine, a voltage-gated sodium channel blocker, has been reported to dose-dependently reduce inflammatory hyperalgesia. However, the antinociceptive effects of carbamazepine on the spinal cord in inflammatory conditions are unclear. The aim of the present study was to evaluate the antinociceptive effects of carbamazepine on the spinal cord in a chronic inflammatory condition.In Sprague-Dawley rats, a chronic inflammatory condition was induced by complete Freund's adjuvant (CFA) inoculation into the tail. Tail flick (TF) latencies were measured following intraperitoneal carbamazepine, or intrathecal carbamazepine or tetrodotoxin injection in intact rats and in the chronic inflammatory rats. From the values of TF latency at 60 min after drug injection, the effective dose required to produce 50% response (ED(50)) of each drug was derived.Carbamazepine attenuated thermal responses with both systemic and intrathecal administration. The effect was more evident in rats with chronic inflammation than in intact rats; the ED(50s) of intraperitoneal carbamazepine in intact and inflamed rats were 12.39 and 1.54 mg/kg, and those of intrathecal carbamazepine were 0.311 and 0.048 nmol, respectively. Intrathecal tetrodotoxin also clearly inhibited the response, with ED(50s) of 1.006 pmol in intact rats and 0.310 pmol in inflamed rats. The relative potencies of intrathecal carbamazepine versus tetrodotoxin for inhibition were approximately 1:150-1:300 in intact and inflamed rats.These results indicate that the inhibition of voltage-gated sodium channels, at least tetrodotoxin-sensitive channels, may contribute to the antinociceptive effect of carbamazepine on CFA-induced inflammatory pain, since lower doses of intrathecal carbamazepine and tetrodotoxin attenuated thermal responses to a greater extent in inflamed rats than in intact rats.

1. Hypertensive patients have pathophysiological changes such as atherosclerosis, endothelial dysfunction and inflammations. The patients' serum nitric oxide metabolite (nitrate/nitrite; NO(x)) levels were measured in peripheral blood using normotensive controls for comparison. 2. The NO(x) levels in 175 hypertensive patients with or without comorbid diseases (aged 37-95 years; average 50.6 +/- 0.8 years) were compared with those in 80 normotensive controls (aged 25-73 years; average 37.1 +/- 1.8 years). 3. The NO(x) levels increased with age in both the normotensive and hypertensive women, but not in men. No difference was noted in the NO(x) levels between the normotensive and hypertensive patients without comorbid diseases. The mean value of NO(x) in male hypertensive patients aged under 50 years was close to that of female patients aged 51-60 years. Hypertensive males aged 61-70 years showed almost the same NO(x) levels as those of female patients aged over 81 years. A male group of hypertensive patients with diabetes, hyperlipaemia and renal disorder had a significantly higher NO(x) level compared with a normotensive control group. However, in female groups, only hypertensive patients with hyperlipaemia showed higher serum NO(x) values compared with the normotensive group. 4. These findings suggest that: (i) the occurrence of NO(x) in the serum is not solely the outcome of high blood pressure; (ii) higher serum NO(x) levels in older women are because of an oestrogen deficiency-induced cardiovascular disease; (iii) ageing effects on the circulation system are more apparent in men than in women; and (iv) measurement of NO(x) levels in the serum is helpful for understanding the pathological progress in male hypertensive patients with diseases such as diabetes mellitus, hyperlipaemia and renal disorder.

We investigated bone mass, tibial bone tissue, and urinary deoxypyridinoline (Dpd), as markers of bone metabolism in experimental osteopenia model (ovariectomized) rats. Decreased bone mass in all rats showed significant positive correlation with increased urinary Dpd. Moreover continuity of trabecular bone was lost in the ovariectomied rats. The findings suggest that the markers of bone metabolism can be utilized for selection of treatment, and/or evaluation of the treatment, and possibly decision-making concerning the start treatment.

In order to examine the effectiveness of running loading therapy for bone mineral density (BMD), we comparatively evaluated measuring methods by computed X-ray absorptiometry (CXD) and assayed urinary deoxypyridinoline (Dpd) for ovariectomized (OVX) rats. Continuous running loading therapy for OVX rats was found to suppress a decrease in mean BMD, and significanfly increase bone metabolic marker compared to normal rats.These results suggest that the assessments of urinary Dpd as well as CXD for osteoporosis diagnosis are reliable and suitable methods.

Objective: To clarify the role of chymase in hypertension,we evaluated the effect of a chymase inhibitor, TY-51469,on vascular dysfunction and survival in stroke-pronespontaneously hypertensive rats (SHR-SP).Methods: SHR-SP were treated with TY-51469 (1mg/kgper day) or placebo from 4 to 12 weeks old or until death.Wistar–Kyoto rats were used as a normal group.Results: SBP was significantly higher in both the placeboand TY-51469 groups than in the normal group, but therewas no significant difference between the two treatmentgroups. Plasma renin, angiotensin-converting enzymeactivity and angiotensin II levels were not differentbetween the placebo and TY-51469 groups. In contrast,vascular chymase-like activity was significantly higher in theplacebo than in the normal group, but it was reduced byTY-51469. Acetylcholine-induced vascular relaxation wassignificantly higher in the TY-51469 group than in theplacebo group. There was significant augmentation of thenumber of monocytes/macrophages and matrixmetalloproteinase-9 activity in aortic tissue from theplacebo group compared with the normal group, andthese changes were attenuated by TY-51469. Therewere also significant increases in mRNA levels ofmonocyte chemoattractant protein-1 and tumornecrosis factor-a in the placebo group that wereattenuated by TY-51469. Cumulative survival wassignificantly prolonged in the TY-51469 group comparedwith the placebo group.Conclusion: Chymase might play an important role invascular dysfunction via augmentation both of matrixmetalloproteinase-9 activity and monocyte/macrophageaccumulation in SHR-SP, and its inhibition may be usefulfor preventing vascular remodeling and prolonging survival.Keywords: chymase, hypertension, inhibitor, macrophage,vascular diseaseAbbreviations: ACE, angiotensin-converting enzyme;MCP, monocyte chemoattractant protein; MDA,malondialdehyde; MMP, matrix metalloproteinase; PRA,plasma renin activity; ROS, reactive oxidative stress; RT-PCR, real-time PCR; SHR-SP, spontaneously hypertensiverats; TNF, tumor necrosis factor; WKY, Wistar–Kyoto

When fibrous collagen of rat tail tendons was glycated by incubation with ribose, it became highly insoluble in dilute acetic acid and resistant to pepsin digestion at 5 degrees C, since it was cross-linked by advanced glycation end products. Extensively glycated fibrous collagen was found to be much less stable than non-glycated control fibrous collagen against pepsin digestion at 30 degrees C. Under conditions where nearly all of the glycated fibrous collagen was degraded into small peptides by pepsin, approximately 45% of the control collagen was left as large polypeptides having nearly the whole length of its triple-helical region. A soluble collagen, which consisted primarily of the triple-helical region of monomeric collagen, was found to be glycated as efficiently as the fibrous collagen on incubation with ribose at 30 degrees C, while the rate of cross-linking of the soluble collagen was very low, suggesting that the triple-helical strands do not undergo intramolecular cross-linking and that most of the cross-links produced in the glycated fibrous collagen are intermolecular ones. The glycated soluble collagen was as stable as the control collagen against pepsin digestion at 30 degrees C. These results indicate that the triple-helical strands of glycated fibrous collagen are much less stable than those of the non-glycated form against proteolytic digestion by pepsin at a temperature close to but below their melting point. Sugar-derived intermolecular cross-links are supposed to underly the decreased stability of the triple-helical strands.

Sodium dodecyl sulfate (SDS), an anionic hydrophobic ligand, is known to alter the mechanical properties of elastic fibers. In order to analyze the mechanism of the alteration, two forms of fibrous elastins, "solid" and "powder" elastins, which consisted of fascicular elastic fibers and single or oligomeric elastic fibers, respectively, were prepared from bovine aorta, and the interactions of SDS with these elastins in the presence and absence of 0.15 M NaCl were studied. The solid elastin was able to retain 1.2- to 1.4-fold larger amounts of SDS than the powder elastin under both conditions, and both elastins retained 1.2-fold or larger amounts of SDS in the presence of NaCl than in its absence. Whereas both elastins released the retained SDS gradually on repeated washing with an SDS-free buffer, the release rates from the solid elastin, especially the rate in the presence of NaCl, were much smaller than those from the powder elastin, and the solid elastin retained approximately 40% of the bound SDS under conditions where the powder elastin lost most of its SDS. The SDS-binding capacities of both elastins were significantly lower than those of soluble kappa-elastin and serum albumin, which bound SDS homogeneously on the polypeptide chains. When the washed SDS-bound solid elastin was incubated with methylene blue and examined under a microscope, most of the methylene blue-SDS complex was located at the interfiber spaces of the elastic fibers. These results suggest that SDS alters the mechanical properties of elastic fibers by binding to the interfiber spaces and surfaces of the fibers rather than by binding to the internal polypeptide chains.

Intracellular free Ca2+, [Ca2+]i, levels were measured in platelets from stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive Wistar-Kyoto rats (WKY) using fura-2AM. In the presence of extracellular Ca2+ (1 mM), [Ca2+]i levels in unstimulated platelets of 2- and 9-month-old SHRSP were both significantly higher than those of the age matched WKY. In the absence of extracellular Ca2+, the levels in platelets from 9-month-old SHRSP were also higher than any other groups examined. Receptor-linked Ca2+ influxes of old SHRSP were smaller when thrombin or collagen was given to the platelets. Phorbol 12-myristate 13-acetate (TPA) enhanced more prominently the Ca2+ influx into old SHRSP platelets than into old WKY platelets. These results strongly suggest that the Ca2+ permeability across plasma membrane is increased in young as well as old SHRSP platelets, where the resting [Ca2+]i level is highly sustained because of an impaired Ca2+ uptake mechanism and possible enhancement of protein kinase C activity.

Ipomoea batatas, Agaricus blazei and Smallanthus sonchifolius are known to favorably influence diabetes mellitus. To clarify their antidiabetic efficacy and hypoglycemic mechanisms, we treated streptozotocin-induced diabetic rats with daily oral feeding of powdered Ipomoea batatas (5 g kg(-1) d(-1)), Agaricus blazei (1 g kg(-1) d(-1)) or Smallanthus sonchifolius (4 g kg(-1) d(-1)) for 2 months. Treatments with Ipomoea batatas or Agaricus blazei, but not Smallanthus sonchifolius, significantly suppressed the increases of fasting plasma glucose and hemoglobin A1c levels, and restored body weight loss during diabetes. Serum insulin levels after oral glucose administration tests increased along the treatments of Ipomoea batatas or Agaricus blazei. Moreover, Ipomoea batatas and Agaricus blazei reduced superoxide production from leukocytes and vascular homogenates, serum 8-oxo-2'-deoxyguanosine, and vascular nitrotyrosine formation of diabetic rats to comparable levels of normal control animals. Stress- and inflammation-related p38 mitogen-activated protein kinase activity and tumor necrosis factor-α production of diabetic rats were significantly depressed by Ipomoea batatas administration. Histological examination also exhibited improvement of pancreatic β-cells mass after treatments with Ipomoea batatas or Agaricus blazei. These results suggest that hypoglycemic effects of Ipomoea batatas or Agaricus blazei result from their suppression of oxidative stress and proinflammatory cytokine production followed by improvement of pancreatic β-cells mass.

The molecular states of collagen in the aortas of age-matched stroke-prone spontaneously hypertensive (SHRSP) and normotensive Wistar Kyoto rats (WKY) were studied by analyzing its extractability under defined conditions. The monomeric and oligomeric collagen extractable with 0.5 M acetic acid/6 M urea from aortic homogenates of 9-month-old SHRSP and WKY comprised approx. 0.6 and 2.0%, respectively, of the total collagen. On incubation of the acetic acid/urea-extracted residues with pepsin at 4 degrees C, the levels of the collagen alpha 1(I) and alpha 2(I) chains solubilized from the SHRSP residues were both less than 50% of those from the WKY residues. When the residues were incubated with pepsin at 15 or 25 degrees C, the differences became smaller. When the acetic acid/urea residues were hydrolyzed with cyanogen bromide, nearly identical peptide maps were obtained for SHRSP and WKY. The aortas from 2-month-old SHRSP and WKY contained much larger proportions of acid/urea-extractable collagen than those of the older rats (8.2 and 13% of the respective total collagen). The levels of the alpha 1(I) and alpha 2(I) chains solubilizable from the respective residues by pepsin at 4 degrees C were similar to each other. These results indicate that aortic collagen fibrils in SHRSP are stiffened more prominently than those in WKY.

Hypoglycemic effects of the extracts of two Siamese plants, Momordica charantia (M.c.) and Phyllanthus urinaria (P.u.), were examined in streptozotocin-induced diabetic rats. Oral administration of a 50% methanol extract (30 mg/kg) of M.c. and P.u. decreased the blood glucose levels (BGL) by 25% and 24%, respectively, at 3 hr after administration. Among other fractions such as the ethyl ether or water soluble fractions, the 10 and 30 mg/kg n-butanol soluble fraction from M.c. extract was most effective in lowering BGL by 26% and 34%, respectively. Similarly with M.c., the n-butanol fraction from P.u. extract decreased BGL by 23% and 39% at the doses of 10 and 30 mg/kg, respectively. In the oral glucose tolerance test, n-butanol fractions from M.c. and P.u. (30 mg/kg, p.o.) both inhibited the initial increase in BGL to the same degree. In the intraperitoneal glucose tolerance test the n-butanol fraction of M.c. inhibited the increase of BGL prominently, but the n-butanol fraction of P.u. did not. These plants generally contain moderately non-polar hypoglycemic compound(s) soluble in n-butanol; and specifically, with regards to the hypoglycemic mechanism, the M.c. extract seems to act like insulin or via insulin secretion from the pancreas, like the action of sulfonyl ureas, and the P.u. extract may act via facilitation of glucose metabolism and/or the inhibition of glucose absorption in the gut like the action of biguanides.

To clarify the relationships between free calcium levels, ATP release and aggregation potencies of SHRSP platelets, we examined the platelets from 9-month-old SHRSP and WKY using fura-2AM and luciferine-luciferase. In the absence of extracellular Ca2+, each reagent elevated the free calcium level to the same extent in the samples of both SHRSP and WKY. With regard to ATP release, thrombin and collagen less potentiated the platelet action in SHRSP than WKY, and ATP release was not affected by extracellular Ca2+. Collagen and ADP induced aggregations showed lower activities in SHRSP than WKY. TPA caused higher Ca2+ influx and aggregation activity in SHRSP than WKY in the presence of extracellular Ca2+. These results indicate that Ca2+ release must be followed by ATP release, and ATP release may be less potentiated, while thrombin and TPA induced aggregation is likely to be stimulated in SHRSP platelets, because protein kinase C activity in SHRSP platelets appears to be high.

It had already showed that several thromboxane A(2) receptor (TP receptor) antagonists might be utilized in the treatment of cardiovascular diseases. In addition, recent reports suggested that TP receptor antagonism may be able to restrict vascular inflammation in atherosclerotic vessels. In particular, S18886 has been developed as a non-prostanoid TP receptor antagonist derived from sulotroban that is characterized by a tetrahydronaphthalene ring as a spacer between the 4-cholophenylsulfonamide group and carboxylic acid. Several reports using experimental animal models of atherosclerosis indicated that S18886 caused a regression of advanced atherosclerosis. More recently, several studies and patents showed that new thromboxane modulators combined with another pharmacological activities have been developed. Ohtake et al. discovered TRA-418 (a benzene-condensed heterocyclic derivative) having a TP receptor antagonistic activity and a prostaglandin I(2) receptor agonistic activity. Cesagrande found that 4-methyl-N- (4-trans-nitrooxycyclohexyl)-N-(3-pyridinylmethyl)-1,3- benzenedicarboxamide is endowed with anti-thromboxane and NO-donor actions. Oketani et al. discovered that E3040, a novel benzothiazole derivative, inhibited TXA(2) synthase and 5-LO activities. EK112, a combined angiotensin II and TP receptor antagonist, was developed. These new compounds may be able to restrict further infiltration of inflammatory cells in atherosclerotic vessels, thus stabilizing vulnerable plaques in the related cardiovascular diseases.

Inflammatory processes may play a pivotal role in the pathogenesis of cerebrovascular injury in salt-loaded stroke-prone spontaneously hypertensive rats (SHRSP). Recent reports revealed that acetylsalicylic acid (aspirin) has anti-oxidative properties and elicits nitric oxide release by a direct activation of the endothelial NO synthase. The present study was designed to determine whether low-dose aspirin might prevent cerebrovascular injury in salt-loaded SHRSP by protecting oxidative damage. Nine-week-old SHRSP were fed a 0.4% NaCl or a 4% NaCl diet with or without treatment by naproxen (20 mg/kg/day), salicylic acid (5 mg/kg/day), or aspirin (5 mg/kg/day) for 5 weeks. Blood pressure, blood brain barrier impairment, mortality, and the parameters of cerebrovascular inflammation and damage were compared among them. High salt intake in SHRSP significantly increased blood brain barrier impairment and early mortality, which were suppressed by treatment with aspirin independent of changes in blood pressure. Salt loading significantly increased superoxide production in basilar arteries of SHRSP, which were significantly suppressed by treatment with aspirin. Salt loading also significantly decreased NOS activity in the basilar arteries of SHRSP, which were significantly improved by treatment with aspirin. At 5 weeks after salt loading, macrophage accumulation and matrix metalloproteinase-9 activity at the stroke-negative area in cerebral cortex of SHRSP were significantly reduced by treatment with aspirin. These results suggest that low-dose aspirin may exert protective effects against cerebrovascular inflammation and damage by salt loading through down-regulation of superoxide production and induction of nitric oxide synthesis.

BACKGROUND Inflammatory processes may play a pivotal role in the pathogenesis of cerebrovascular injury in salt-loaded, stroke-prone, spontaneously hypertensive rats (SHRSP). Thromboxane A2 (TP) receptor stimulation by 8-iso-prostaglandin F2alpha (8-iso-PGF2alpha) is involved in the process of vascular inflammation. OBJECTIVE In the present study, we examined the involvement of TP receptor in the development of cerebrovascular damage in salt-loaded SHRSP. METHODS Nine-week-old SHRSP were fed a 0.4% NaCl or a 4% NaCl diet with or without ONO-8809 treatment (a TP receptor antagonist) for 5 weeks. Blood pressure, mortality, and the parameters of cerebrovascular inflammation and damage were compared between the groups. Moreover, we examined the effect of 8-iso-PGF2alpha infusion on cerebrovascular injury of SHRSP. RESULTS High salt intake in SHRSP significantly increased blood-brain barrier impairment and early mortality, which were suppressed by ONO-8809 treatment independent of changes in blood pressure. Salt loading also significantly increased superoxide production in basilar arteries of SHRSP, which was suppressed by ONO-8809 treatment. Macrophage accumulation and matrix metalloproteinase-9 (MMP-9) activity in the stroke-negative area in the contralateral cerebral cortex to the stroke lesion of salt-loaded SHRSP and 8-iso-PGF2alpha-treated SHRSP were significantly reduced by ONO-8809 treatment. The ONO-8809 treatment prevented thinning of the vessel layer in cerebral arterioles of salt-loaded SHRSP and 8-iso-PGF2alpha-treated SHRSP. CONCLUSIONS These results suggest that TP receptor stimulation by 8-iso-PGF2alpha may involve salt loading-induced stroke through activation of cerebrovascular inflammation and damage.

1. Placental Na+, K+ -ATPase activities were measured in connection with the active transport of amino acid, intra-uterine growth retardation (IUGR) or small for date infants (SFD) in salt-loaded pregnant SHRSP. 2. All parameters such as fetal weight, placental weight and Na+, K+ -ATPase activity in the placental tissue were significantly depressed in SHRSP, especially in the salt-loaded SHRSP compared with WKY. 3. Besides a decrease of blood flow, a decline of Na+, K+ -ATPase activity associated with an active transport of amino acid in the placenta would cause IUGR and SFD in the salt-loaded pregnant SHRSP. 4. Pregnant SHRSP given water containing salt would be a good model for pregnancy induced hypertension in humans.

1. The experiments were carried out by an ordinary and a microsphere method in order to clarify the effects of three nitric oxide-synthase inhibitors and -donor on the circulating system between SHRSP and WKY. 2. Intravenous administration of each compound possessing the nitric acid-synthase inhibiting action markedly elevated the systolic blood pressure both in SHRSP and WKY, but more prominently in the former. 3. The hypotensive and tachycardic responses to glyceryl trinitrate were more enhanced after treatment with NG-nitro-L-arginine and NG-nitro-L-arginine methyl ester but not with NG-monomethyl-L-arginine compared with the non-treated one. 4. All peripheral organs except the brain decreased their regional blood flow after administration of NG-nitro-L-arginine, indicating a crucial involvement of nitric oxide in the peripheral circulation. 5. It was suggested that the nitric oxide system worked more sensitively and actively in SHRSP than in WKY in order to maintain the peripheral blood flow and systemic blood pressure.

Summary 1. The aim of the present study was to examine the effects of isoteoline (IST), a new tetrahydroaporphine derivative, on the blood pressure and some of the components of renin-angiotensin-aldosterone system (RAAS) in spontaneously hypertensive rats (SHR). 2. After long-term treatment (14 days, 3 times daily) in a dose of 1 mg/kg orally and intraperitoneally, IST induced a significant decrease of the systolic blood pressure (SBP) in SHR (from 192 ± 2 to 155 ± 5 mgHg). 3. At the same time, IST induced a significant decrease of the levels of plasma renin activity (PRA) and aldosterone (ALD) and manifested a trend to increase the sodium plasma level. 4. These results indicate that IST after chronic long-term treatment induced a marked antihypertensive effect and inhibited the components of RAAS in SHR. Apparently, the long-lasting antihypertensive effect of IST in SHR was mediated and realized in part by inhibition of the components of RAAS.

Cardiovascular disease is one of the most important causes of morbidity and mortality in diabetes mellitus, but there has been controversy over functional impairment of diabetic hearts and their tolerance to ischemia. We studied ischemic heart function in type 2 diabetic rats with different degrees of hyperglycemia and its relationship with cardiac norepinephrine release. Otsuka Long-Evans Tokushima Fatty rats (OLETF) and age-matched Long-Evans Tokushima Otsuka normal rats (LETO) were used. One group of OLETF rats was given 30% sucrose in drinking water (OLETF-S). Hearts were isolated and perfused in a working heart preparation and subjected to 30 min ischemia followed by 40 min reperfusion at age of 12 months. Hemodynamics and coronary norepinephrine overflow were examined. Fasting plasma glucose in OLETF increased markedly at 12 months and sucrose administration exacerbated hyperglycemia in diabetic rats (LETO 6.6 +/- 0.5, OLETF 8.3 +/- 0.7, OLETF-S 15.0 +/- 1.7 mmol/L, P < 0.01). Basic cardiac output in OLETF was decreased as compared with LETO and OLETF-S (LETO 29.4 +/- 2.5, OLETF 24.0 +/- 2.4, OLETF-S 27.0 +/- 0.9 ml/min/g, P < 0.05) and remained very low after ischemia, while in OLETF-S it was well preserved (OLETF 4.2 +/- 2.1, OLETF-S 13.7 +/- 2.6 ml/min/g, P < 0.01). Correspondently, cardiac norepinephrine released during ischemia and reperfusion was lower in OLETF-S (OLETF 2.3 +/- 1.0, OLETF-S 0.7 +/- 0.1 pmol/ml, P < 0.01). Thus, OLETF hearts were more vulnerable to ischemia but sucrose feeding rendered their hearts resistant to ischemia. Less norepinephrine release may play a role in preventing postischemic functional deterioration in sucrose-fed diabetic hearts.

Summary: Although mammalian ventricle is richly supplied with adrenergic nerves, endogenous norepinephrine is not essential to the intrinsic contractility of the normal heart. However, it is not clear whether acute changes in cardiac norepinephrine could alter heart function in genetically hypertensive rats. The purpose of this study was to examine the effect of cardiac norepinephrine reduction on basal and postischemic heart function in stroke-prone spontaneously hypertensive rats (SHRSPs) using an isolated working heart preparation. Hypertrophied hearts of SHRSPs showed higher cardiac norepinephrine content and impaired heart function at 4 months of age as compared with normal Wistar-Kyoto rats. Poor postischemic recovery of heart function observed in SHRSPs was accompanied by large amounts of coronary norepinephrine overflow. Cardiac norepinephrine reduction or depletion did not affect basal heart function in SHRSPs. Considerable reduction in cardiac norepinephrine with acute reserpine injection (5 mg/kg) in SHRSPs significantly improved postischemic recovery of cardiac output, coronary flow, and rate-pressure product. However, complete norepinephrine depletion with reserpine (10 mg/kg) was detrimental to myocardial automaticity and limited the postischemic recovery of systolic function in the hypertrophied hearts. These results suggest that acute reduction in cardiac norepinephrine may be of potential therapeutic importance to postischemic dysfunction in the hypertrophied hearts.

The reactivity of intrarenal arteries to vasoconstrictor and vasodilator polypeptides was examined in adult stroke-prone spontaneously hypertensive rats (SHRSP). The contraction response to endothelin-1 (ET-1) was greater in SHRSP than in age-matched Wistar-Kyoto rats (WKY), and so was the pD2 estimate (8.05+/-0.03 in SHRSP, and 7.73+/-0.06 in WKY; n=5, P < 0.05). The contraction response to, and the pD2 estimate of, vasopressin were comparable in SHRSP and WKY. Neuropeptide Y did not contract the intrarenal arteries. In norepinephrine-precontracted arteries with intact endothelium, substance P and neurokinin A did not relax the arteries of either SHRSP or WKY, while calcitonin gene-related peptide (CGRP) induced a profound relaxation response. Relaxation response to CGRP was significantly greater in SHRSP than in WKY. Atrial, brain, and C-type natriuretic peptides (ANP, BNP, CNP), vasoactive intestinal polypeptide (VIP), and peptide histidine isoleucine (PHI) all caused relaxation responses, with a greater extent of relaxation to ANP, BNP, and VIP and a less extent to CNP and PHI. However, there were no significant differences in these relaxation responses between SHRSP and WKY. The current results revealed the character of heterogeneity of rat intrarenal arteries in response to vasoconstrictor and vasodilator peptides, and showed an enhanced reactivity to ET-1 and to CGRP in SHRSP.

1. The acute effects of nitric oxide synthase inhibition on the haemodynamics in stroke-prone spontaneously hypertensive (SHRSP) and normotensive Wistar-Kyoto (WKY) rats were investigated using radiolabelled microspheres. 2. Intravenous administration of 3 and 6 mg/kg NG-nitro-L-arginine (L-NNA) caused a significant increase in total peripheral resistance, a decrease in cardiac output and an increase in blood pressure in both SHRSP and WKY rats. 3. Significant decreases in regional blood flow (RBF) in the lung, muscle and stomach of WKY rats were observed following L-NNA administration. 4. NG-nitro-L-arginine produced a 70% increase in brain regional blood flow at a dose of 6 mg/kg only in SHRSP. 5. There was a variation in the involvement of nitric oxide (NO) in different tissues. 6. It is concluded that hypertension in SHRSP augments NO-mediated vasodilation.

Epigallocatechin-3-gallate suppresses transforming growth factor-beta signaling by interacting with the transforming growth factor-beta type II receptor

1. The effect of environmental temperature on the indirect measurement of rat blood pressure and heart rate was investigated with special reference to the tail arterial blood flow in both strains of SHRSP and WKY. 2. Very good correlations (r > 0.82, P < 0.05; t-test, 10 d.f.) were observed between the two values of systolic blood pressure or heart rate measured by a direct and an indirect method at environmental temperatures between 26 and 38 degrees C in SHRSP, and 34 and 38 degrees C in WKY, respectively. 3. When the temperature was elevated by 10 degrees C from 25 degrees C to 35 degrees C, the regional blood flow in the tail artery increased by 52-69%, sufficient to detect a blood flow increase by the indirect method. 4. These data showed that the best way to measure the accurate blood pressure and heart rate in both strains of SHRSP and WKY by the indirect volume-oscillometric method was to hold the rats at 34-36 degrees C for 5 min.

Summary 1. Vessel wall fragments consisting of collagen, elastin and other insoluble proteins were prepared from the aortas of 6 month old WKY and SHRSP and dead, elderly humans. 2. Prolonged incubations of these fragments with pepsin below or at 30°C resulted in different amounts of insoluble materials containing similar or larger proportions of collagen and other insoluble proteins than the respective vessel fragments. The amounts of the pepsin-insoluble materials obtained from SHRSP were larger than those from WKY but were much smaller than those from elderly humans. 3. The elastins isolated from the vessel fragments were solubilized by pepsin much more effectively than the respective vessel fragments. 4. The pepsin-insoluble materials from WKY were composed of thin mesh-shaped materials, while those from SHRSP were composed of denser sheet-shaped materials. While these materials from both rats did not contain a significant number of distinctive fibrils of collagen, the materials from elderly humans did contain numerous distinctive fibrils of collagen. 5. Large fractions of both the collagen and other proteins in the pepsin-insoluble materials were solubilized by incubation with a crude bacterial collagenase below 30°C or by incubation with pepsin above 40°C where the triple-helical regions of the collagens were unfolded. 6. These results appear to indicate that the aortic wall of SHRSP contains larger amounts of some insoluble components that immobilize the collagen fibrils than that of WKY, but the aortic walls of elderly humans contain much larger amounts of these components than that of SHRSP.

Contractile proteins were extracted from thoracic aortae of 9-month-old spontaneously hypertensive stroke-prone (SHRSP) and normotensive Wistar Kyoto rats (WKY). The average wet weight of the aortae from SHRSP was approximately 1.6-fold heavier than that of WKY. On polyacrylamide gel electrophoresis of the myofibrillar extracts prepared from normalized, equal weights of aortae of SHRSP and WKY, both the compositions and concentrations of major polypeptides including myosin heavy chains and actin were nearly identical in these extracts. The myosins purified from these extracts contained identical light chains of about 20- and 17 kDa. Proteolytic peptide maps of the heavy chains of myosin from SHRSP were also indistinguishable from those of WKY, suggesting that the same isoforms of myosin are expressed in both aortae. From these results it is suggested that the qualitative differences may be small, if any, between the major contractile proteins in the aortae of SHRSP and those of WKY.

The andrenocorticotrophic effect of a synthetic substituted adrenocorticortophic hormone (ACTH), alpha-1-18NH2-D-Ser1-Lys17, 18-ACTH (CIBA 47, 795-Ba) has been compared with that of alpha1-24-ACTH (tetracosactide), alpha1-24-ACTH depot (tetracosactide depot) and alpha1-18NH2-Gly1-ACTH (giractide) in the rabbit. Plasma corticosteroid levels after salin injection were higher in the afternoon than in the morning. The highest value was observed at 3 p.m. 41,795-Ba, either given intravenously or intramuscularly, was shown to be the most potent peptide followed by tetrocosactide depot and was 15 times more potent than tetracosactide and giractide in steroidogenic activity in the rabbit. The intravenous administration of 41,795-Ba caused more sustained stimulation of the adrenal cortex than the intramuscular injection. These results reveal the diurnal variation pattern of the pitutitary-adrenal axis of the rabbit similar to that of the rat and also confirm the finding that alpha1-18NH2-Dser1-Lys17, 18-ACTH is a potent adrenocorticotrophic peptide without the addition of any agent to delay its absorption in the rabbit.

By using the isolated seminal vesicles of guinea pigs, the effects of dibutyryl cyclic AMP and beta-stimulant, orciprenaline, on the responses to Ca, K, acetylcholine and Ba were investigated, especially in relation to cyclic AMP. The following results were obtained.1. Orciprenaline inhibited the contractions produced by Ca, K, acetylcholine and Ba in a dose-dependent manner, and the inhibition became larger in the order of Ca, K, acetylcholine and Ba. 2. Dibutyryl cyclic AMP showed the same results as those of orciprenaline. That is, dibutyryl cyclic AMP inhibited the contractions produced by the tested contractile agents. The inhibition became larger in the order of Ca, K, acetylcholine and Ba. 3. Orciprenaline showed the increased level of cyclic AMP in a dose-dependent manner. But the increase was not remarkable in the concentration in which the contractions pro duced by the tested contractile agents were inhibited by about 50%.From these results, the following suggestions were obtained; (1) there exsists beta-receptor in guinea pig seminal vesicles and (2) a part of actions of orciprenaline is due to a mechanism unrelated to cyclic AMP.