Adrenal medulla is involved in the aldosterone secretagogue effect of substance P

Substance P (SP) increased aldosterone secretion of rat adrenal slices, but not of isolated zona glomerulosa cells, and this effect was annulled by two specific antagonist of SP (SP-A). Both tissue preparations displayed an aldosterone secretory response to isoprenaline (IP) that was blocked by l-alprenolol (AL). AL reversed the aldosterone response of adrenal slices to IP, SP, or IP plus SP, whereas SP-A only suppressed that to SP. Quarters of adrenocortical autotransplants, which are completely deprived of chromaffin cells, showed an aldosterone response to IP, but not to SP. These findings suggest that the mechanism underlying the aldosterone secretagogue action of SP probably involves the stimulation of catecholamine release by adrenal medulla chromaffin cells.