THE EFFECT OF HUMAN GROWTH HORMONE ON SUBCUTANEOUS FAT THICKNESS IN HYPOSOMATOTROPHIC AND PANHYPOPITUITARY DWARFS

Abstract

Zona glomerulosa cell suspensions with less than 5% fasciculata-reticularis cell contamination were prepared by collagenase digestion of normal rat adrenal capsular tissue. The corticosterone and aldosterone content of such cell suspensions under various conditions were measured simultaneously. Increases in steroid production were observed with physiological concentrations of angiotensin 11 (2 × 10⁻¹¹ mol/l), with sigmoid log dose-response curves for both corticosterone and aldosterone production (ED₅₀:4 × 10⁻¹⁰ and 8 × 10⁻¹⁰ mol angiotensin II/l respectively). The response to angiotensin II could be abolished by [Sar¹, Ala⁸]-angiotensin II; 50% inhibition was produced by an equimolar concentration of this antagonist. Extracellular potassium ion concentration was shown to affect steroid output dramatically, confirming previous observations and underlining its importance as a physiological regulator of aldosterone secretion. The characteristics of the effect of serotonin, a potent stimulator of steroidogenesis in this system, were also observed. Differences in the maximal responses to angiotensin II and serotonin could not be explained by degradation and probably reflect their different modes of action. Zona fasciculata-reticularis cell suspensions were prepared in a similar fashion from decapsulated adrenal glands, and showed no increase in steroid production with those concentrations of angiotensin II (2 × 10⁻¹¹ to 2 × 10⁻⁷ mol/l) that stimulated glomerulosa cells. However, angiotensin II amide did increase corticosterone production in isolated fasciculata-reticularis cells at concentrations greater than 2 × 10⁻⁵mol/l, as reported by others, whereas angiotensin free acid did not. It is concluded that this sensitive rat glomerulosa cell suspension will be useful for studying the modes of action of angiotensin II and other stimulators of aldosterone biosynthesis.