PROXIMAL TUBULAR REABSORPTION DURING RENAL VASODILATION AND INCREASED ARTERIAL BLOOD PRESSURE IN SALINE LOADED RATS

Rats were infused with 0.31 ml per min isotonic saline + bicarbonate intravenously. A further infusion of acetylcholine and bradykinin into the renal artery resulted in natriuresis, diuresis, an increase in PAH clearance and a higher content of hemoglobin in the kidney tissue; blood pressure and inulin clearance remained constant. After acetylcholine infusion, a shortening of transit time of Lissamine green through the proximal convolution and a narrowing of tubuli were observed without significant change in reabsorptive t1/2 (split-oil-droplet). After bradykinin infusion, these changes were much smaller and insignificant. It seems therefore, that a common mechanism of natriuresis after kidney vasodilation does not probably exist. The changes in renal parameters of saline-bicarbonate infused rats after body overheating (natriuresis and diuresis, an increase in PAH clearance and hemoglobin content, shortening of transit time and narrowing of tubuli) were probably due to an elevation of blood pressure. If this increase was prevented by an aortic clamp just below the diaphragm, all values did not differ from those in control rats. © 1969 Springer-Verlag.