The effects of sodium loading on cardiopulmonary baroreflexes.

1. The effects of sodium loading on cardiopulmonary baroreflex control of forearm vasoconstriction were studied using lower body negative pressure (LBNP) in 12 healthy young subjects. 2. Before and during sodium loading, there was no significant change in mean blood pressure, heart rate, central venous pressure (CVP) or forearm vascular resistance (FVR). 3. The degree of reflex increase in FVR during LBNP at -10, -20, and -40 mmHg was significantly greater during sodium loading than regular diet. 4. During sodium loading, the slope of the regression line relating percent change in FVR and change in CVP was significantly increased. 5. These results suggest that sodium loading augments cardiopulmonary baroreflex sensitivity of FVR in normotensive subjects without a family history of hypertension.