Acceleration of Renal Hypertension Accompanied by Increase in Plasma Volume as a Result of Prior Thoracic Sympathectomy

Abstract

The renal pressor system exerts a dramatic effect on body fluid volumes when the thoracic sympathetic chains are removed in dogs. This effect was demonstrated in experiments designed originally to determine the influence of cardiac sympathectomy on the increase in cardiac output that precedes development of renal hypertension. While removal of the cardiac sympathetic nerve supply did not prevent the increase in cardiac output after wrapping one kidney in cellophane, a modest rise in blood pressure was accompanied by a remarkable 46 ± 8 (S.E.) % (p < 0.005) increase in plasma volume at the expense of interstitial fluid space. Removal of the contralateral kidney caused the appearance of malignant hypertension within 6 to 56 days while the plasma volume decreased somewhat though it remained well above control values. Unwrapping the kidney restored the blood pressure and fluid volumes to normal. Infusion of small dosage of angiotensin for 5 days into two other dogs after removal of the thoracic sympathetic chains had a similar effect on plasma volume; infusions were without effect prior to sympathectomy. The findings uncover an as yet unexplained interaction between the renal pressor and sympathetic nervous systems.