No abstract

No abstract

To determine the major stimuli for the release of brain natriuretic peptide (BNP) and atrial natriuretic peptide (ANP), we measured their plasma concentrations in 14 normal subjects and 19 patients with essential hypertension during exercise with a bicycle ergometer. The plasma levels of both hormones at baseline were significantly higher in the hypertensive group than in the controls (p < 0.05). The exercise raised both the plasma BNP and ANP, with concomitant increases in systolic blood pressure (SBP), heart rate (HR) and plasma norepinephrine (NE) or epinephrine (Epi) in each group. In the controls the change in ANP correlated with those in SBP, HR and NE (p < 0.05), and similarly the change in BNP with those in SBP, HR, NE and Epi (p < 0.05). In multivariate regression analysis only NE was found to be a significant stimulus for ANP secretion, whereas SBP or Epi was related to BNP release. In the hypertensives the change in ANP correlated with those in HR and NE, but on multivariate regression analysis the change in ANP correlated only with that in HR. The change in BNP in the hypertensives correlated only with that in HR. These findings indicate that in normal subjects the exercise-induced release of BNP and ANP is more sensitive to a similar but slightly different sympathetic stimulus, whereas in hypertensives the major stimulus for the release of both hormones is heart rate, indicating that the mediators for BNP or ANP release are altered by some factors involved in hypertension.

1. The haemodynamic effects of rat adrenomedullin (AM), a novel hypotensive peptide, were examined in anesthetized 16-18 week old spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY). 2. An intravenous injection of rat AM dose-dependently reduced the mean blood pressure (MBP) with a concomitant fall in total peripheral resistance index (TPRI) and an increase in cardiac index (CI) in both strains of rats. Percent changes in MBP, TPRI and CI were not different between SHR and WKY. 3. The plasma half-life of rat AM in SHR was similar to that in WKY when it was administered at the dose of 1.0 nmol/kg. 4. These findings indicate that AM has a potent vasorelaxant activity in both SHR and WKY. The haemodynamic responsiveness to exogenous AM and its pharmacokinetics in SHR were comparable with those in WKY.