Effect of 60-minute head-down tilt on arterial baroreflex function in anesthetized dogs

Arterial baroreflex control of heart rate was assessed in 6 anesthetized dogs with a bolus infusion of phenylephrine before and during cardiopulmonary receptor stimulation by 6 degrees head-down tilt (HDT) for 60 min. No difference in arterial baroreflex function was observed between the control and HDT conditions. It appears that the attenuation of baroreflex function that occurs during acute stimulation of cardiopulmonary baroreceptors disappears when cardiopulmonary baroreceptors reset after prolonged stimulation.