The interaction between renin-angiotensin system and sympathetic nervous system in the peripheral vasculature of normal Sprague-Dawley rats

To evaluate possible interactions between the renin-angiotensin system (RAS) and the sympathetic nervous system (SNS) in the systemic circulation upon the intravenous administration of angiotensin 2 and a set of adrenergic agonists in normal Sprague-Dawley (SD) rats. Rats were treated with carvedilol, a non-selective β- and selective α₁-adrenoceptor blocker, in a dose of (5 mg/kg) orally for 7 days, and on day 8, the animals were pentobarbitone-anaesthetized and prepared for systemic hemodynamic study. Dose-response relationships in terms of elevation in the magnitude of the mean arterial blood pressure in response to intravenous injection of noradrenaline (NA), phenylephrine (PE), methoxamine (ME), and angiotensin 2 (Ang 2) were determined. Data, mean ± S.E.M., were subjected to ANOVA with signifcance at P < 0.05. Carvedilol blunted the peripheral vascular response to NA, PE, ME, and Ang 2 (all P < 0.05). It is concluded that peripheral vasoconstriction induced by Ang 2 is contributed to by adrenergic action. Furthermore, there is a cross-talk relationship between RAS and SNS in determining the responsiveness of the peripheral vasculature to adrenergic agonists and angiotensin 2 in normal rats.