Intrarenal secretion of renin in the dog: effect of furosemide.

RAILIE, MICHAEL D., LARRY E. DAVIS, AND RODGER LOUTZENI-USER. Intrarenal secretion of renin in the dog: effect of furosemide. Am. J. Physiol. 224(2) : 425-430. 1973.-The activity of the renin was measured in systemic arterial plasma and renal hilar lymph following volume expansion with isotonic saline and after the intravenous administration of furosemide in volume-expanded dogs. lienin activity was consistently greater in renal lymph than in plasma, although the concentration of angiotensinogen in plasma was equal to or slightly greater than that in lymph. Volume expansion resulted in suppression of renin activity in both plasma and lymph. Following administration of furosemide, renin activity increased in both plasma and lymph despite the volume expansion. Furosemide administration was followed by an increase in renal blood flow and a decrease in glomerular filtration rate. These hemodynamic changes appear to reflect efferent arteriolar vasodilatation; therefore, it is unlikely that the hemodynamic changes are controlled by the renin-angiotensin system. One explanation for the higher renin activity in lymph may be the small volume of the renal interstitial space as compared to the systemic plasma volume. Secretion of renin into the svstemic circulation and into the renal interstitial space appears to take place in a parallel manner.