Long-term effects of captopril on the morphology of normal rat adrenal zona glomerulosa. A morphometric study.

The effects of a long-term administration of captopril (Squib 14225) on the rat zona glomerulosa were investigated. Morphometry showed that this drug, which specifically inhibits angiotensin-converting enzyme, induces a notable atrophy of zona glomerulosa cells, which is principally due to the decrease in the volume of mitochondrial compartment and smooth endoplasmic reticulum. Radioimmunological assays disclosed that in the treated rats the plasma aldosterone concentration is significantly lowered. The suppressive effects of captopril were completely reserved by chronic treatment with angiotensin II. These findings confirm the view that the renin-angiotensin system is involved in the maintenance of the growth and steroidogenic capacity of the normal rat zona glomerulosa.