Reflex vasopressin and renin modulation by cardiac receptors in humans

Animal studies have shown that vasopressin secretion is modulated by arterial baroreceptors and cardiopulmonary volume receptors. Whether this is the case also in humans is controversial, however. To determine whether vasopressin is reflexly modulated by cardiac volume receptors, we studied the effect on plasma vasopressin (venous blood, radioimmunoassay) of reducing venous return and left ventricular end-diastolic diameter (echocardiography) by producing a 20-minute lower body negative pressure in 14 healthy subjects (aged 49.3±3.8 years, mean±SEM). The data were compared with those of 14 age-matched heart-transplant recipients, i.e., subjects with cardiac denervation. In healthy subjects, lower body negative pressure at -15 mm Hg caused a modest reduction in left ventricular end-diastolic diameter (- 5±3.4%) and no change in vasopressin, whereas lower body negative pressure at -37.5 mm Hg caused a more marked reduction in left ventricular end- diastolic diameter (-12±2.5%) and a small, variable, but overall statistically significant (p>0.05) increase in vasopressin (+145±46%, p