Angiotensin II helps maintain or raise the intraglomerularpressure by preferentially vasoconstricting efferent glomerular arterioles resultingin glomerular filtration rate (GFR) autoregulation.8 By blocking the renin-angiotensin system in renovascular hypertension, thismechanism is disturbed and a reduction in GFR occurs. This evidence concerns the gene REN and renovascular hypertension.