THE EFFECT OF EPINEPHRINE UPON FROG RENAL HEMODYNAMICS IN THE INTACT ANIMAL

Publisher Website
Google Scholar
Abstract
The effects of epinephrine on frog renal hemodynamics as studied by the indirect clearance methods are precisely the same as those noted by direct observation of the functioning kidney. This is interpreted as constituting further evidence for the reliability of clearance methods in evaluating the various aspects of renal activity. The adm. of small amts. of epinephrine into the circulation results in decreasing the renal blood flow, increasing the filtration fraction and, hence, maintaining a constant rate of glomerular filtration. This effect is obtained by causing constriction of the efferent glomerular arteriole. Constriction of the afferent arteriole accompanied by decreased renal blood flow, filtration fraction, filtration rate and number of functioning glomeruli results from the administration of massive doses of epinephrine. In the normal frog, unlike mammals, afferent control of the glomerular circulation plays an important role in the regulation of glomerular activity. Variations in the rate of water elimination result primarily from alterations in rate of glomerular filtration and only secondarily from variations in the rate of tubular water reabsorp-tion.