Endothelin effects on renal function and tubuloglomerular feedback

Analysis of our data in conjunction with other recent literature allows the following conclusions regarding the role of endothelin in the tubuloglomerular feedback control mechanism and in the pathogenesis of acute ischemic renal failure: (1) Endothelin reduces nephron filtration rate in the nephrons with interrupted signal perception at the macula densa, in accord with preglomerular arteriolar constriction. Yet, the increase in filtration fraction in the whole kidney clearance study suggests a preferential postglomerular arteriolar constriction. Taken together, endothelin, which is a very potent renal vasoconstrictor, seems to constrict both preglomerular and postglomerular arterioles with a predominant constriction of the latter at the doses employed. (2) The endothelin-induced natriuresis is due to a fall in tubular reabsorption, reflecting a direct tubular action, possibly related to an elevation in blood pressure. (3) At the doses of endothelin used and under the present experimental conditions, changes in the magnitude of tubuloglomerular feedback (TGF) response or the feedback characteristic could not be detected. (4) No evidence was found for a participation of endothelin in the pathogenesis of acute postischemic renal failure, as evidenced by the absence of an improvement in glomerular filtration after treatment with endothelin antiserum.