EFFECT OF CHRONIC CONVERTING-ENZYME INHIBITION ON KIDNEY-FUNCTION OF SENESCENT HYPERTENSIVE RATS

The age-related changes in the structure and the function of the kidne y and the effect of chronic inhibition of angiotensin-converting enzym e (ACE) activity on these alterations were assessed in senescent, gene tically hypertensive rats. Mean blood pressure was unchanged between 6 and 21 months, being 136 +/- 10 and 135 +/- 21 mm Hg, respectively. H ypertrophy of the glomeruli with a high incidence of glomerulosclerosi s was reported in the 21-month-old animals. Renal blood flow, glomerul ar filtration rate, and filtration fraction were reduced between 6 and 21 months, whereas albuminuria and cGMP excretion were markedly enhan ced with aging. Chronic ACE inhibition by administration of 0.3 mg/kg/ day trandolapril from 18-21 months increased the life expectancy of th e animals without affecting their mean blood pressure. The incidence o f glomerular lesions and the excretion of enzymes that reflected the i ntegrity of tubular and glomerular cells were not altered by ACE inhib ition. On the other hand, the filtration fraction was restored in the 21-month-old treated animals, and the age-related albuminuria and rise in cGMP excretion were prevented by ACE inhibition. These results ind icated that ACE inhibitor administered at the end of the life of senes cent hypertensive rats was able to prevent some of the age-related cha nges in kidney function when glomerulosclerosis was already present.