The nature of the action of renin and hypertensin on renal function in the rabbit

The effects of combined renal vasodilatation and pressor agents on renal hemodynamics and the tubular reabsorption of sodium.

“…We have suggested previously that increased renal medullary blood flow may diminish the absolute reabsorption of sodium by the ascending limb of Henle's loop (4,5), and Leyssac has suggested that angiotensin may diminish proximal tubular reabsorption of sodium (15). Although the effects have not been entirely predictable, angiotensin does produce natriuresis under some conditions (16)(17)(18)(19). If diminished renal blood flow increased sodium reabsorption in Henle's loop or more distal portions of the nephron, then the vasoconstrictor effects of angiotensin could mask the effects that the agent could have to diminish proximal reabsorption by enhancing sodium reabsorption at a more distal site, and perhaps also by reducing GFR and the filtered load of sodium.…”

“…Furthermore, natriuresis in the absence of salt loading accompanies increased renal blood flow when local vasodilatation is produced by a variety of agents (7)(8)(9)(10)(11)(12)(13), and we have observed that the unilateral natriuresis accompanying increased renal blood flow during the renal arterial infusion of acetylcholine is due in part to diminished net tubular reab-sorption of sodium (14). Leyssac has suggested that angiotensin may depress proximal tubular reabsorption (15), and it has been demonstrated that under certain conditions angiotensin may produce natriuresis (16)(17)(18)(19). If the reabsorption of sodium distally to the proximal convolution relates in part in some inverse manner to blood flow, then the vasoconstrictor effects of angiotensin could limit the natriuretic effect that the agent could exert by way of depressing proximal tubular reabsorption.…”

Angiotensin II directly stimulates sodium transport in rabbit proximal convoluted tubules.

“…Since the demonstration by Hughes-Jones et al in 1949 (6) that systemic infusions of a crude renin preparation produced natriuresis, numerous investigators have examined the role of the renin-angiotensin system, and particularly All, in renal salt and water transport. Clearance studies in several species demonstrated that, in general, systemic infusion of All at rates <100 ng kg-'-min-' produced antinatriuresis, whereas higher infusion rates produced natriuresis (7).…”

THE EFFECT OF EPINEPHRINE (USP), l-EPINEPHRINE, AND l-NOREPINEPHRINE ON GLOMERULAR FILTRATION RATE, RENAL PLASMA FLOW, AND THE URINARY EXCRETION OF SODIUM, POTASSIUM, AND WATER IN NORMAL MAN 12

“…Associated changes in urine formation might be predicted but have not as yet been clearly defined. In animals, I-epinephrine seems to give rise to a water diuresis and augmented excretion of chloride (4)(5)(6)(7)(8), whereas in man both agents may diminish urine flow (1,2). A study of the effect of pure l-epinephrine and l-norepinephrine upon renal hemodynamics, and excretion of water and electrolytes in normal human subjects was undertaken in order to clarify this problem.…”