Graded reductions of atrial pressure and renin release

Publisher Website
Google Scholar
Abstract
A study was done to assess the effects of graded reductions of atrial pressure on renin secretion in Na-restricted dogs, anesthetized with chloralose and breathing spontaneously. Distention of the superior vena cava-right atrial junction, was applied for 5 min by means of a balloon inflated to 4, 8 and 14 cm3 and was associated with significant and progressive reductions in right atrial pressure at each level of distention. At 4 and 8 cm3 levels of distention the reductions in atrial pressure were not associated with any change in mean aterial blood pressure or mean renal blood flow. Renin secretion, calculated as the product of the renal venous minus arterial renin activity (radioimmunoassay) and renal blood flow, was increased significantly at the 4 and 8 cm3 levels of distention. For these lower levels of distention, it was possible to demonstrate a graded increase in renin secretion with the graded decrease in right atrial pressure. These findings are consistent with the neurogenic control of renin release, originating with the reductions in atrial pressure. At the 14 cm3 level of distention, the reduction in right atrial pressure was associated with no change in mean arterial pressure, but a significant reduction of renal blood flow. Renin secretion was not significantly increased at 14 cm3 distention in spite of the reduction in right atrial pressure. At this level of distention a more complex interaction of neurogenic and hemodynamic mechanisms influencing renin release is suggested.