Abstract

This study investigates the contribution of central vasopressin receptors in the modulation of systolic arterial pressure (SAP) and heart rate (HR) response to air-jet stress in conscious Wistar rats equipped with a femoral arterial catheter and intracerebroventricular cannula using novel non-peptide and selective vasopressin V_1a (SR49059) and V_1b (SSR149415) antagonists. The effects of stress on SAP and HR were evaluated by measuring the maximal response to stress, the latency of the maximal response, the duration of the recovery period, and the increase in the low frequency (LF) short-term variability component. Stress induced a parallel and almost immediate increase in both SAP and HR, followed by enhanced LF SAP variability in the recovery period. Pretreatment of rats with V_1a antagonist did not affect the maximal increase or the latency of SAP and HR response to acute stress, but shortened the recovery period of SAP and HR and prevented the increase in LF SAP. The V_1b antagonist reduced the maximal increase in SAP without affecting HR and their latencies, shortened the recovery period of SAP and inhibited the increase in LF SAP variability. These results indicate that both central V_1a and V_1b receptors mediate cardiovascular changes induced by air-jet stress in conscious rats.