Physiological actions of angiotensin II on the kidney.

The importance of angiotensin as a modulator of renal function is well documented. Several lines of evidence suggest strongly that angiotensin plays an important role in the maintenance of renal vascular resistance and arterial pressure in several physiological and pathophysiological states with increased activity of the renin-angiotensin system. Angiotensin also acts as a physiological "brake" on excessive release of renin from juxtaglomerular cells. Angiotensin influences renal sodium excretion via its renal vascular actions to change the glomerular filtration rate and, thus, the filtered load of sodium; in addition, angiotensin influences tubular reabsorption of sodium by altering the filtration fraction and the balance of Starling forces in the peritubular capillaries.