Indomethacin inhibits the basal and angiotensin II-stimulated mitotic activity of adrenocortical cells in vivo and in organ culture.

The aim of the experiment in vivo was to examine the effect of a 3-day peroral administration of indomethacin (IND: 4.0-4.7 mg/kg b.wt./24 h) on the adrenocortical cell proliferation in rats in basal conditions and after a single i.p. injection of angiotensin II (ANG: 100 micrograms per rat). The in vitro study was to test the effect of IND on the mitotic incidence in adrenocortical cells or organ-cultured rat adrenal explants during a 24-h incubation with or without ANG. It was shown that IND significantly decreased the mean mitotic activity rate (MMAR) of adrenocortical cells in vivo as well as in organ culture. That decrease concerned all the three cortical zones vs respective controls. In turn, both in vivo and in vitro ANG markedly increased the MMAR of the zona glomerulosa cells as compared to the values recorded in controls, while there were no changes of the MMAR of the zona glomerulosa after ANG in the groups receiving IND. The results obtained indicate that IND exhibits an inhibitory effect on the adrenocortical cell proliferation which may suggest that prostaglandins (PGs) play an important role in the process of adrenocortical hyperplasia, their participation in the ANG-induced zona glomerulosa cell proliferation being strongly assumed.