Effects of Calcium on the Potassium and Sodium Content of Rat Adrenal Glands, on the Stimulation of Steroid Production by Adenosine 3′,5′-Monophosphate, and on the Response of the Adrenal to Short Contact With Acth

Abstract

The potassium content of incubated rat adrenal tissue is significantly higher when calcium is present in the incubation medium than when it is absent. The effect of calcium on the sodium content of the adrenal depends upon the presence of ACTH; increased values are obtained with calcium in the presence of ACTH, decreased values in its absence. There is no correlation between the potassium or sodium content of the tissue and its ability to respond to ACTH. Adenosine 3′,5′-monophosphate triples the steroid output of incubated adrenal glands in the absence of both glucose and calcium. Addition of calcium further doubles this response while glucose has only a small effect. The stimulation of steroid production following short contact with ACTH does not depend upon the presence of calcium or glucose in the medium during the time the glands are exposed to the hormone. The results suggest that some step between contact of the tissue with ACTH and the elaboration of adenosine 3′,5′-monophosphate requires the presence of glucose and not necessarily calcium and that a reaction in the sequence between elaboration of the nucleotide and steroid production requires the presence of calcium, but not of glucose.

Lanthanum: inhibition of ACTH-stimulated cyclic AMP and corticosterone synthesis in isolated rat adrenocortical cells.

“…The requirement for Ca + § in the steroidogenic response of the adrenal cortex to A C T H was first described many years ago (5,41). Since then it has been shown that in the steroidogenic action of ACTH, Ca ++ is required for the formation of the second messenger, cyclic A M P (2,19,26,28,31,49), as well as for reactions after the formation of this cyclic nucleotide (6,13,21,24,47,49). A number of investigators have studied the role of Ca ++ in the ACTH-stimulation of cyclic A M P formation, in both intact and broken cell preparations.…”

“…Besides t Deceased 8 August 1975.the well-documented effects on the Ca+ +-dependent "excitation-contraction" coupling in the muscle, reviewed recently by Weiss (57), La +++ has also been reported to affect "stimulus-secretion" coupling in a number of systems that are believed to require Ca ++ as the coupling agent. These include .catecholamine release from the adrenal medulla (8), histamine release from mast cells (14), and oxytocin-induced milk ejection from the mammary gland (30).The requirement of Ca ++ for the steroidogenic effect of ACTH as well as that of cyclic AMP has been known for many years (5,6,41). More…”

“…The requirement of Ca ++ for the steroidogenic effect of ACTH as well as that of cyclic AMP has been known for many years (5,6,41). More…”

On the mode of action of ACTH on the isolated perfused adrenal gland

“…Previous studies have already shown that calcium is needed for optimal steroid production and release in vitro (Birmingham et at. 1960;Triller & Birmingham, 1965), and it has been suggested from studies on broken cell preparations, which do not respond to ACTH, that the action of calcium is to promote the intramitochondrial synthesis of corticosteroids (see Peron & McCarthy, 1968).…”

“…However, this inhibition of the steroidogenic effect of ACTH observed during calcium deprivation might be ascribed to the accumulation of steroid within the cortical cell, i.e. endproduct inhibition (Birmingham & Kurlents, 1958;Ferguson, Morita & Mendelsohn, 1967), although one cannot rule out that calcium deprivation might also directly suppress steroidogenesis in the intact adrenal, just 553 SIRET D. JAANUS AND OTHERS as it does in quartered adrenals (Birmingham et al 1960), and in brokencell preparations (Peron & McCarthy, 1968).…”