Right atrial stretch decreases supraoptic neurosecretory activity and plasma vasopressin.

It is generally held that left atrial stretch (LAS) but not right atrial stretch (RAS) reflexly inhibits vasopressin release and results in a diuresis. To reexamine the influence of RAS on the release of vasopressin and on the behavior of antidromically identified supraoptic neurosecretory neurons, RAS and LAS were applied in pentobarbital-anesthetized cats. Weighted 20 or 30 g sutures were placed in the left atrium pulmonary vein junction and at the base of the right atrial appendage. Antidromically identified supraoptic nucleus neurons were inhibited by both RAS and LAS applied independently and together, although fewer neurons were responsive to RAS alone. Simultaneous stretch of both atria resulted in greater inhibition of these neurons than did stretch of either atrium alone. Stretch of the right atrium alone also resulted in a significant decrease in plasma arginine vasopressin measured by radioimmunoassay. Differences between these results and other reports may stem from differences in the method of RAS or the specific right atrial receptors affected.