Blockade of angiotensin II AT1 receptors inhibits pressor action of centrally administered interleukin-1β in Sprague Dawley rats

The aim of the present study was to evaluate the influence of intraventricular administration of recombinant rat interleukin-1 beta (IL-1 beta) oil regulation of resting blood pressure and heart rate and to test the hypothesis that the brain angiotensinergic system is involved in regulation of hemodynamic parameters by centrally applied IL-1 beta. The experiments were performed on Sprague Dawley rats, assigned to three series or experiments. In series 1 (control, n = 6), mean arterial pressure (MAP) and heart rate (HR) were recorded for 15 min under baseline conditions. This was followed by infusion of saline (0.9% sterile NaCl 5 mu L/h) into the left cerebral ventricle (LCV). Measurements were continued during the next 60 min. In series 2 (n = 6) and 3 (n = 6) the experimental design was similar, except that in series 2 the animals were LCV infused with saline containing IL-1 beta (100 ng/h) and in series 3 with saline containing IL-1 beta (100 ng/h) and angiotensin type 1 (AT1) receptors antagonist (Losartan, 10 mu g/h). LCV infusion of saline alone did not influence MAP and HR while administration of IL-1 beta elicited significant increase in MAP, but not in HR. The pressor effect was absent during combined infusion of IL-1 beta and Losartan. Results of the study provide evidence that centrally administered IL-1 beta exerts pressor effect, and reveal that this effect is mediated by stimulation of the brain angiotensin system and requires activation of AT1 receptors. (c) 2005 Elsevier Ltd. All rights reserved.