| Abstract: | Factors controlling proliferation of adrenocortical cells have been studied in monolayer cultures of bovine adrenocortical cells. Angiotensin II stimulated cell proliferation and 3H]thymidine incorporation into DNA with a half-maximal effective concentration of 0.96 +/- 0.27 nM. Similar sensitivity to angiotensin III with reduced sensitivity to angiotensin I and tetradecapeptide renin substrate was observed. Although sensitivity to angiotensin II was equivalent to that for fibroblast growth factor (1.5 nM half-maximal effective concentration), maximal effects of angiotensin were less than for fibroblast growth factor and serum. High concentrations of insulin (1-10 micrometer) also stimulated 3H]thymidine incorporation into DNA and cell proliferation. Sar1,Ile5,Ile8]Angiotensin II, a competitive antagonist of angiotensin II, blocked angiotensin II stimulation of DNA synthesis but did not affect fibroblast growth factor and insulin stimulation of DNA synthesis. Corticotropin (ACTH) blocked the stimulatory effects of both angiotensin II and fibroblast growth factor. The dose-response curves for angiotensin II stimulation of steroidogenesis were similar to those for stimulation of 3H]thymidine incorporation into DNA. Among the seven cell types examined, only adrenocortical cells responded to angiotension II with stimulation of DNA synthesis. |
