Subject(s)
AIDS-Related Opportunistic Infections/drug therapy , Antiviral Agents/therapeutic use , Cytosine/analogs & derivatives , Cytosine/therapeutic use , Mouth Diseases/drug therapy , Organophosphonates/therapeutic use , Warts/drug therapy , Adult , Cidofovir , HIV-1 , Humans , Male , Middle Aged , PapillomaviridaeABSTRACT
Two questions were investigated to elucidate the adrenal function of arginine vasopressin (AVP) in controlling aldosterone secretion: Are vasopressin tissue concentrations in the adrenal modulated by diets that influence aldosterone secretion? Does its direct stimulation of aldosterone secretion from adrenal cells in vitro suggest that vasopressin plays an important role in controlling aldosterone? Diets that modulate aldosterone secretion from rat adrenals did not modulate concentrations of AVP in this tissue: Adrenal AVP concentrations did not differ significantly between rats on low- and high-sodium (22.9 +/- 3.8 and 32.4 +/- 6.4 pg/g) or between low- and high-potassium (25.6 +/- 2.5 and 12.5 +/- 7.3 pg/g) diets. Although the existence of AVP receptors on adrenocortical cells incubated in vitro and the stability of AVP during cell incubation was confirmed, AVP had only a minor direct effect on steroid secretion in short-term incubations alone and in combination with angiotensin II (A II), potassium and atrial natriuretic factor (ANF). The importance of AVP for an indirect control of aldosterone secretion in vivo is discussed.
Subject(s)
Adrenal Cortex/metabolism , Adrenal Glands/metabolism , Aldosterone/biosynthesis , Arginine Vasopressin/metabolism , Potassium, Dietary/pharmacology , Sodium, Dietary/pharmacology , Adrenal Cortex/cytology , Adrenal Cortex/drug effects , Adrenal Glands/drug effects , Angiotensin II/pharmacology , Animals , Arginine Vasopressin/pharmacology , Atrial Natriuretic Factor/pharmacology , Cell Membrane/metabolism , Cyclic GMP/biosynthesis , Female , In Vitro Techniques , Iodine Radioisotopes , Male , Potassium, Dietary/antagonists & inhibitors , Rats , Rats, Wistar , Receptors, Vasopressin/biosynthesis , Zona Glomerulosa/metabolism , Zona Glomerulosa/ultrastructureABSTRACT
We investigated the effect of high physiological plasma levels of human varies; is directly proportional to atrial natriuretic factor (ANF) on renin and aldosterone secretion in normal sodium deplete men. In short term infusion studies (2 or 8 h duration), ANF plasma levels as observed after sodium loading (50-70 pg/ml) lowered basal renin (PRA) and aldosterone, but had only a marginal effect on angiotensin II-stimulated aldosterone secretion. Preliminary results of a study with long term infusion (6 days) of ANF during a period of dietary sodium depletion argue against a significant tonic inhibitory effect of ANF on the renin-aldosterone system in the preceding period of sodium repletion: the plasma aldosterone response to sodium depletion was similar with and without ANF infusion. The second messenger of ANF for the direct inhibition of aldosterone secretion from zona glomerulosa cells is still unknown. To test the hypothesis, that cGMP is the second messenger of ANF, we produced a rise in intracellular cGMP in rat and rabbit zona glomerulosa cells using the unspecific phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX) and the more cGMP specific phosphodiesterase specific inhibitor M + B2948 (Zaprinast). Both inhibitors simulated the action of ANF in suppressing steroid secretion and elevating cGMP levels. The results are compatible with the view that cGMP is of importance as a second messenger for ANF in adrenal zona glomerulosa cells. Selective inhibition of phosphodiesterases in combination with endopeptidase inhibition may be an interesting principle to enhance the action of endogenous and exogenous ANF.
