A local renin-angiotensin system in the human adrenal gland: evaluation of in vitro secretion by a non-parametric combination of randomness permutation tests.

The aim of this study is to assess the mode of release of renin, angiotensin II and aldosterone during in vitro superfusion of the human adrenal gland using a non-parametric combination of four randomness tests. Five normal adrenals and four aldosteronomas superfused over 270 mins were found to concomitantly release renin, angiotensin II and aldosterone. The pattern of this release exhibited a significantly non-random pulsatile character in 17 out of 23 single hormone series (p < 0.05). A further statistical combination-test analyzing the release of each hormone for all experiments with normal and pathological tissue, respectively, showed significant pulsatility (p < 0.01) in 5 out of 6 groups. The pulsatile mode of in vitro hormone release by the human adrenals indicates an active secretory process rather than a discharge of tissue-stored forms. The source of such intra-adrenal intrinsic pulse-generating mechanism could reflect the periodic course of a negative biological feedback reaction.