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Horm Metab Res 1975; 7(2): 184-189
DOI: 10.1055/s-0028-1093775
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© Georg Thieme Verlag KG Stuttgart · New York

Adenyl Cyclase Activity in Rat, Ovine and Human Adrenal Preparations

A.  Dazord , D.  Gallet , J. M. Saez
  • Unité de Recherches Endocriniennes et Métaboliques chez l'Enfant, INSERM, U. 34, Hôpital Debrousse, Lyon, France
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Publication Date:
23 December 2008 (online)

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Abstract

The adenyl cyclase activity was studied in subcellular preparations (crude membranes: 20,000 × g pellet) of rat, human and ovine adrenals.

In the three species a stimulation by fluoride, ACTH, EDTA and EGTA was found. But EGTA and EDTA appear to act through different mechanisms. Exogenous calcium inhibits the basal enzyme activity, but the stimulation induced by ACTH is retained. There are two pools of endogenous calcium, one inhibits the basal activity of adenyl cyclase, the other is essential for the stimulation induced by ACTH. Simultaneous examination of the different factors stimulating adenyl cyclase indicated at least two pools of enzyme molecules, one stimulated by ACTH, a second by prostaglandins, and possibly a third by EDTA and EGTA. Sodium fluoride appeared to stimulate a pool common to the first two pools.

Every tested factor affects maximum velocity of the enzyme without any significant change of the affinity of ATP for adenyl cyclase.

Key words

Adrenal - Adenyl Cyclase - Prostaglandins - ACTH - EGTA - Calcium