GLOMERULAR NUMBER AND SIZE FOLLOWING CHRONIC ANGIOTENSIN-II BLOCKADE IN THE POSTNATAL RAT

Chronic angiotensin-converting enzyme (ACE) inhibition with enalapril or angiotensin II (Ang II) receptor antagonism with either losartan (s pecific for Ang II type-1 receptor, AT(1)) or PD 123319 (specific for the Ang II type-2 receptor, AT(2)) were effected between postnatal day s 3 and 21 in the rat. Following quantitative analysis of the kidneys using recently developed unbiased stereological techniques we found th at none of the treatments resulted in changes in glomerular number or size. This implies that inhibition of Ang II activity had no effect on postnatal nephron induction or glomerular development. However, follo wing both chronic ACE inhibition and AT(1) antagonism, abnormalities o f tubules and their associated vessels were evident throughout the kid ney and were accompanied by an increased proportion of interstitium. T he structural abnormalities were most prominent in the outer medulla a nd were consistent with interruption of descent of the loops of Henle and vasa rectae. In contrast, no renal morphological abnormalities wer e observed following chronic AT(2) antagonism.