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Background The haemodynamic effects of intravenous infusion of the non-selective nitric oxide synthase (NOS)l-omega monomethyl arginine (l-NMMA) have previously been characterized in humans. Its effect of reducing cardiac index (CI) is an important reason for the increase in mortality in patients with septic shock receivingl-NMMA in a pivotal outcome trial for this indication. The mechanism for the reduction in CI however, is uncertain. Methods In this study, we investigated the haemodynamic and arterial stiffness response to a bolus intravenous infusion ofl-NMMA (3 mg kg−1 over 5 min) in 26 healthy human volunteers to clarify the likely cause ofl-NMMA induced negative inotropic and chronotropic effects. Digital photoplethysmography (MicroMedical Pulse Trace) was used to derive two measures of arterial stiffness: stiffness index, a measure of large arterial stiffness, and reflection index (RI), a measure of small- to medium-sized arterial stiffness. Haemodynamic measurements of systolic blood pressure, diastolic blood pressure, heart rate, systemic vascular resistance index (SVRI), stroke index and CI were made using a bioimpedance monitor (BioZ Cardiodynamics). Results We found that changes in CI duringl-NMMA are closely related to changes in RI and SVRI. Conclusion The negative inotropic effect ofl-NMMA may be a result of an increase in coronary vascular resistance and a resultant decrease in myocardial perfusion. The reduction in CI may also result from a direct reduction of the normal positive inotropic effect of NO byl-NMMA which is closely correlated with its effects on SVRI. [ABSTRACT FROM AUTHOR]

Aims: To determine the prevalence of isolated systolic hypertension (ISH) in patients 60 years of age and over attending general practitioners, and the proportion of patients in whom blood pressure (BP) remains within the ISH range when measured on three successive occasions and when using home BP monitoring. Methods: BP was measured in 38 832 patients. Patients categorized as having ISH were reviewed after one week. Patients who had BPs in the ISH range at the second visit were provided with a home BP monitor and attended again in one week's time for further clinic blood pressure measurements. Results: 8.6% of all patients were classified as having ISH and 31.4% as having borderline ISH at the first clinic visit. ISH was twice as prevalent in patients receiving antihypertensive therapy (12.4%) than in those not on antihypertensive therapy (6.2%). Of the patients initially categorized as having ISH, and who attended all three clinic visits and completed the home BP monitoring, 52.3% were confirmed as having ISH, 34.0% fell into the borderline ISH range and only 7.0% had a normal BP reading at the third clinic visit. The use of home BP monitoring produced similar results. Conclusion: ISH is present on first screening in approximately 8% of elderly Australian patients. This prevalence falls by about 50% when BP is measured on two further occasions, with most patients subsequently falling into the borderline ISH range. Home BP monitoring does not reduce the percentage of patients classified as having ISH on the basis of three clinic measurements. [ABSTRACT FROM AUTHOR]

Noradrenaline (NA), adrenaline (A) and dopamine (DA) levels were measured in the heart, kidney and caudal artery of male and female SHR and WKY rats aged 6, 14 and 28 weeks, and the influence of strain, sex and age on catecholamine content determined., Levels of A were elevated in all three regions of SHR compared to WKY rats, independent of age and sex. This may represent increased A accumulation in sympathetic nerves resulting from the increased sympatho-adrenomedullary hyper-reactivity of the SHR strain., DA levels were also elevated in the heart and kidney of SHR rats, independent of sex and age., NA levels were lower in the heart of SHR rats, but this appeared to be partly a consequence of cardiac hypertrophy and partly due to strain differences between older male but not female rats. Thus a simple association between decreased cardiac NA levels and hypertension appeared unlikely., It is emphasised that further genetic studies of F2 backcross rats would be required to establish an etiological association between these differences in catecholamine levels and differences in blood pressure between the SHR and WKY strains. [ABSTRACT FROM AUTHOR]