Hydrostatic pressure enhances baroreceptor reflexes in the rat.

The effects of increased hydrostatic pressure on baroreceptor reflexes in the decerebrate rat have been investigated. Baroreceptor 'sensitivity' was assessed from the relationship between cardiac interval and systolic blood pressure following infusion of phenylephrine to animals exposed to increases in hydrostatic pressure (1-30 bar) with helium. Resting heart rate and systolic blood pressure were reduced and the 'sensitivity' of the baroreflex heart rate response was significantly increased by exposure to pressure. This enhancement of cardiovascular reflex function, elicited by moderate increases in hydrostatic pressure may, in part, be centrally mediated.