Effects of digitalis on cardiopulmonary baroreflex in man.

We examined whether digitalis augments cardiopulmonary baroreflex control of forearm vascular resistance in normal young men. Cardiopulmonary baroreceptor input was reduced with lower body negative pressure (LBNP) at 10 and 20 mmHg which decreased central venous pressure (CVP) but did not alter blood pressure (BP) or heart rate (HR). Decreases in forearm blood flow and increases in forearm vascular resistance with LBNP were greater after cedilanid than before and the slope of the regression line relating changes in central venous pressure and those in forearm vascular resistance was steeper after cedilanid. Vasoconstrictor responses to a cold pressor test did not differ before and after cedilanid, which suggested that augmented responses to LBNP after cedilanid were not due to a generalized change in reflex control. These results suggest that cedilaniid augments the tonic inhibitory influence of cardiopulmonary baroreceptors in normal men.