The effects of long-term lithium administration on glomerular structure and intervention with angiotensin converting enzyme inhibitor (ACEI) were studied in rats. Male Wistar rats were fed a lithium-containing diet (Li) or control diet (C) for 16 weeks postnatally. Li-treated rats developed renal failure, hypertension and proteinuria. During the subsequent 24 weeks, subgroups were treated with ACEI. The kidneys were fixed by perfusion, and tissue blocks were serially cut for estimation of glomerular volume and glomerular characteristics by light microscopy. Mesangial and mesangial matrix volume fractions, surface density of capillary walls, basement membrane thickness and foot process width (FPW) were measured by electron microscopy. Glomerular volume was decreased in Li-rats, with increased intra-individual variation. In all Li-rats, some glomeruli (mean 27%) were abnormal, with severe changes in only three rats. Ultrastructural parameters obtained by systematic sampling of three glomeruli in each rat showed no differences among groups. Among Li-treated animals there was a significant correlation between FPW and albumin excretion per unit filtration surface, and between filtration surface per glomerulus and inulin clearance. In conclusion, long-term lithium administration to newborn rats caused marked changes in glomerular volume which were not associated with measurable changes in structural parameters. No effect of ACEI-treatment was detectable.
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