Reflex vasopressin and renin modulation by cardiac receptors in humans.

Abstract

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, radiolmmunoassay) 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<0.01). The left ventricular end-diastolic diameter changes induced by the two lower body negative pressure stimuli were similar in heart-transplant recipients, but the vasopressin increase seen with the lower body negative pressure at -37.5 mm Hg was abolished. The marked increase in plasma renin activity and forearm vascular resistance induced by lower body negative pressure in healthy subjects was also abolished or drastically attenuated in heart-transplant recipients. The abolition of the responses was not due to a generalized hyporeactivity because, in heart-transplant recipients, vasopressin, plasma renin activity, and forearm vascular resistance increased normally when stimulated by hyperosmolarity, angiotensin converting enzyme inhibition, and cold, respectively. Thus, in humans vasopressin is modulated reflexly by cardiac volume receptors, although to a limited degree and only for large changes in central blood volume. The reflex influence of cardiac receptors extends to plasma renin activity and vascular resistance, indicating a role of these receptors in both blood volume and blood pressure control. antidiuretic hormone (ADH) vasopressin is modulated not only by changes in plasma osmolality but also by changes in blood volume. '-6 They have also shown that changes in blood volume act by altering the inhibitory influences of arterial baroreceptors on ADH secretion through alterations in blood pressure.3 " 5 They act even more effectively, however, by altering a similar inhibitory influence originating from cardiopulmonary receptors through alterations of the intrathoracic blood content. 6 -8 Whether cardiopulmonary receptors and baroreceptors are involved in modulation of ADH secretion in

Effect of standing on neurohumoral responses and plasma volume in healthy subjects

“…It has been reported in animals and in humans that secretion of AVP is modulated not only by changes in plasma osmolarity but also by changes in BV through baroreflex activation. We found a correlation betwee PV changes and AVP plasma levels that suggests the power of the volume in the modulation of the AVP secretion (15,26). Also, there was a correlation between AVP and urinary osmolality, which is the main factor that determines urine concentration to save water on the assumption of the upright posture.…”

Classical and Delayed Orthostatic Hypotension in Patients With Unexplained Syncope and Severe Orthostatic Intolerance

“…Vasopressin levels increased 3-fold in healthy subjects during HUT (21,22) and a similar increase was seen in patients with autonomic failure and falling blood pressure on HUT, but the increase was not sufficient compared with the magnitude of blood pressure fall (21). Studies have shown that the subnormal vasopressin response in patients with autonomic dysfunction is caused by a defect in the baroreflex arc (23,24).…”

Radial Artery Flow-Mediated Dilatation in Heart Failure Patients

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