Effects of adrenomedullin 2 on regional hemodynamics in conscious rats

The present study aimed to assess the effects of rat adrenomedullin 2 on systemic and regional hemodynamics in conscious Wistar Kyoto (WKY) rats and spontaneously hypertensive rats (SHRs). Intravenous infusion of rat adrenomedullin 2 (0.25-5 mu g/kg/min) decreased blood pressure, and increased heart rate in a dose-dependent manner in both types of rats. Rat adrenomedullin 2 (5 mu g/kg/min) increased heart rate and cardiac output. As a result, total peripheral resistance significantly decreased. In SHRs, adrenomedullin 2 significantly increased regional blood flow in the heart, liver, spleen, kidneys, and adrenal glands. Especially, effects on heart, liver, and kidneys were remarkable. Regional hemodynamic changes were reproduced in WKY rats, and there was no qualitative difference in regional responses to rat adrenomedullin 2 between SHRs and WKY rats. Thus, rat adrenomedullin 2 predominantly increased flow rates in organs that were richly blood-supplied from cardiac output. Rat adrenomedullin 2 may contribute to the regulation of the cardiovascular system, by acting as a local vasodilatory hormone as well as a circulatory hormone. (c) 2006 Elsevier B.V. All rights reserved.