Interaction between carotid and cardiopulmonary baroreflexes in control of plasma ADH

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Abstract
The purpose of this study was to determine if there is an interaction between carotid baroreceptors (CBR) and cardiopulmonary receptors with vagal afferents (CPVA) in the control of plasma vasopressin (ADH). Changes in ADH (radioimmunoassay) in the superior vena cava were determined in 13 chloralose-anesthetized dogs with aortic nerves sectioned during concomitantly induced changes in CBR and CPVA input. CBR input was changed by altering pressure (CSP) in the isolated perfused sinuses. Carotid sinus pressure (CSP) was initially set at 50 mmHg. The CPVA input was reversibly interrupted by cooling the vagi to 0 degrees C while CSP was concomitantly increased to 135 or 200 mmHg or was held constant at 50 mmHg. Vagal cold block (VCB) with CSP held constant at 50 mmHg resulted in large increases in arterial pressure and plasma vasopressin. Increases in CSP to 200 mmHg resulted in significant decreases in arterial pressure and in plasma vasopressin despite concomitant VCB. VCB and concomitant increase in CSP to 135 mmHg resulted in a significant fall in arterial pressure, whereas plasma vasopressin tended to increase. Thus, the influence on arterial pressure of raising CSP to 135 mmHg exceeds that of VCB. In contrast, the influence of VCB on ADH equals or exceeds that of raising CSP to 135 mmHg. These differential responses of arterial pressure and plasma ADH suggest an interaction between CBR and CPVA in the control of ADH and arterial pressure.