Role of adenosine A1 and A2 receptors in the regulation of aldosterone production in rat adrenal glands

To investigate the roles of adenosine A1 and A2 receptors in the regulation of aldosterone production, we examined the effects of adenosine and adenosine agonists (N6-cyclohexyl adenosine; selective adenosine A1 receptor agonist and 5'-N-ethylcarboxamine adenosine; selective adenosine A2 receptor agonist) on aldosterone and cyclic AMP production in rat adrenal capsular cells. Neither adenosine nor 5'-N-ethylcarboxamine adenosine caused significant effects on basal aldosterone or cyclic AMP production. Also, adenosine (10(-3) M) showed no consistent effects on aldosterone and cyclic AMP production induced by ACTH. On the other hand, N6-cyclohexyl adenosine exhibited a significant inhibition of basal aldosterone and cyclic AMP production at doses of 10(-4) M and 10(-3) M; furthermore, 10(-3) M N6-cyclohexyl adenosine inhibited aldosterone and cyclic AMP production stimulated by ACTH. These results suggest that adenosine A1 receptors are coupled to and inhibit adenylate cyclase and may be involved in the inhibition of aldosterone production.     

Circadian rhythm of apical Na-channels and Na-transport in rabbit distal colon

Summary In vivo and in vitro studies showed that electrogenic sodium transport in rabbit distal colon is modulated by aldosterone. It varies in a circadian rhythm; the external synchronizer is the light-dark cycle. The site of regulation was found to be in the apical membrane of colonic epithelial cells, in which the number of conducting sodium-channels is increased by aldosterone.     

Vergleichende Untersuchungen über die hypertensive Wirkung von Aldosteron und Desoxycorticosteron

Summary In the adrenalectomized and unilaterally nephrectomized rat an investigation has been carried out on the influence of a four weeks' treatment with aldosterone and desoxycorticosterone-acetate in doses which are equieffective concerning sodium retaining capacity. Desoxycorticosterone-acetate produced hypertension, perivascular granuloma and renal lesions, whereas under the influence of aldosterone the blood pressure remained normal and no histopathological alterations could be found. Towards the end of the experiment the animals treated with desoxycorticosterone-acetate took up twice as much drinking fluid as the animals treated with aldosterone. Although the results obtained so far are only of a preliminary character it is obvious that aldosterone in doses which are equieffective concerning sodium retention does not produce the same side effects as desoxycorticosterone-acetate.     

Induction of the synthesis of thymidine kinase by aldosterone in the kidney of the immature male rat

Summary Thymidine kinase activity was studied in kidneys from immature male rats after administration of aldosterone. Kinetic studies showed that the enzyme activity reached its maximum level 24 h after aldosterone injection. That increase was specific for aldosterone and could be related to the synthesis of new molecules of enzyme.     

Induction of the synthesis of thymidine kinase by aldosterone in the kidney of the immature male rat

Thymidine kinase activity was studied in kidneys from immature male rats after administration of aldosterone. Kinetic studies showed that the enzyme activity reached its maximum level 24 h after aldosterone injection. That increase was specific for aldosterone and could be related to the synthesis of new molecules of enzyme.     

Plasma aldosterone in newborn and adult Vipera aspis

In the venomous viviparous snake Vipera aspis, plasma aldosterone concentration shows significant seasonal changes mainly related to temperature-dependent behavior. A difference is also present between newborns and adults. A correlation between sodium and potassium status and aldosterone plasma level in active and inactive life is suggested.     

Role of adenosine A1 and A2 receptors in the regulation of aldosterone production in rat adrenal glands

Summary To investigate the roles of adenosine A₁ and A₂ receptors in the regulation of aldosterone production, we examined the effects of adenosine and adenosine agonists (N⁶-cyclohexyl adenosine; selective adenosine A₁ receptor agonist and 5-N-ethylcarboxamine adenosine; selective adenosine A₂ receptor agonist) on aldosterone and cyclic AMP production in rat adrenal capsular cells. Neither adenosine nor 5-N-ethylcarboxamine adenosine caused significant effects on basal aldosterone or cyclic AMP production. Also, adenosine (10^–3M) showed no consistent effects on aldosterone and cyclic AMP production induced by ACTH. On the other hand, N⁶-cyclohexyl adenosine exhibited a significant inhibition of basal aldosterone and cyclic AMP production at doses of 10^–4 M and 10^–3 M; furthermore, 10^–3 M N⁶-cyclohexyl adenosine inhibited aldosterone and cyclic AMP production stimulated by ACTH. These results suggest that adenosine A₁ receptors are coupled to and inhibit adenylate cyclase and may be involved in the inhibition of aldosterone production.     

Plasma aldosterone in newborn and adultVipera aspis

Summary In the venomous viviparous snakeVipera aspis, plasma aldosterone concentration shows significant seasonal changes mainly related to temperature-dependent behavior. A difference is also present between newborns and adults. A correlation between sodium and potassium status and aldosterone plasma level in active and inactive life is suggested.     

Evidence for an unusual multifunctional protoreceptor in hormone action

Summary Contrary to the techniques of mere association, column chromatography has revealed a protoreceptor that accepts aldosterone agonists and antagonists only in the physiological target, the kidney, and is absent in non-targets, liver and serum; it is furthermore different from the aldosterone specific receptor in renal cytosol.Supported in part by grants from the CNRS AI 03 1917 and UER Broussais Hôtel Dieu.     

Potentiating effect of aldosterone on the diuretic action of atrial extract

The typical stimulatory effect of a rat heart atrial extract on urinary water, sodium, potassium and kallikrein excretion is significantly increased by a previous administration of aldosterone (0.5 microgram/100 g b. wt) in the rat.     

Inhibition of aldosterone synthesis induced by flow-stop in the Mongolian gerbil adrenal gland superfused in vitro

Stopping of superfusion flow for short periods resulted in a significant accumulation of aldosterone within the Mongolian gerbil adrenal gland superfused in vitro. Aldosterone amounts in the first 2-min samples after the re-starting of superfusion were positively correlated with the length of flow-stop; however, they were significantly lower than calculated amounts: 5-min stop: 37 +/- 1% inhibition, 10-min stop: 51 +/- 1% inhibition. In addition, aldosterone secretion was significantly suppressed during prolonged incubation. The results suggest that aldosterone and glucocorticosteroid amounts in adrenal tissue may modulate basal corticosteroidogenesis and that self-suppression forms an important part of the control mechanisms involved in corticosteroidogenesis.     

Structures of 9 oligosaccharides and glycopeptides containing large amounts of fucose excreted in the urine of 2 patients with fucosidosis]

Binding of corticosterone and aldosterone to plasma proteins of the edible Frog was studied by equilibrium dialysis technique. A high-affinity, transcortin-like, corticosterone binding system has been demonstrated, but, in vivo, the unbound fraction of this corticosteroid is higher that the bound one. Hypophysectomy and thyroidectomy do not change corticosteroids binding parameters which are modified by a variation of temperature.     

In vitro effect of dexamethasone in conversion of 4-14C progesterone in the fetal rat adrenal glands

Summary It was found that dexamethasone in vitro inhibited the synthesis of corticosterone and aldosterone.This research was supported by Grant No. IV/3 from the Scientific Fund of the Socialist Republic of Croatia, Zagreb Yugoslavia.     

In vitro cAMP,aldosterone and cortisol responses of adult human adrenocortical tissue to ACTH and human growth hormone

Summary The acute in vitro effects of ACTH and HGH in human adrenals were examined. HGH acts synergistically with ACTH in augmenting adrenal aldosterone output. This effect is not due to cAMP alterations in response to HGH. HGH slightly depresses the human adrenal cortisol response to ACTH.     

Potentiating effect of aldosterone on the diuretic action of atrial extract

Summary The typical stimulatory effect of a rat heart atrial extract on urinary water, sodium, potassium and kallikrein excretion is significantly increased by a previous administration of aldosterone (0.5 g/100 g b. wt) in the rat.     

Antagonistic action of E and F series prostaglandins upon mineralocorticoid production by the human adrenal

Summary At long time intervals, the E and F prostaglandins exert antagonistic effects on aldosterone production in vitro. At short intervals the E prostaglandins tend to mimic the inhibitory effect of the PGF series.     

Nuclear localization of aldosterone in rat brain cells assessed by autoradiography

Summary Autoradiographic studies with³H aldosterone demonstrate nuclear concentration of hormone in neurons of the hippocampus, septum, allocortical regionss and brain stem reticular formation and motor nuclei of cranial nerves and in the meninges. The results suggest that mineralocorticoids have wide ranging effects on different parts of the central nervous system.This work was supported by the Medical Research Council of Canada and by PHS grant NS09914. We thank Ms Brenda McClain for technical assistance.     

Corticosteroidogenesis by isolated human adrenal cells: effect of serotonin and serotonin antagonists.

The direct effect of serotonin and antiserotonin agents on adrenal steroid biosynthesis was studied in isolated adrenal cells derived from patients with Cushing's syndrome. The results indicate that serotonin increases corticosterone production, while the serotonin antagonists cyproheptadine and methysergide depress adrenal steroid - particularly cortisol and aldosterone - biosynthesis.     

Nuclear localization of aldosterone in rat brain cells assessed by autoradiography.

Autoradiographic studies with 3H aldosterone demonstrate nuclear concentration of hormone in neurons of the hippocampus, septum, allocortical regions and brain stem reticular formation and motor nuclei of cranial nerves and in the meninges. The results suggest that mineralocorticoids have wide ranging effects on different parts of the central nervous system.