Beta‐adrenergic regulation of cyclic adenosine 3‘,5’ monophosphate accumulation in human gastric epithelial glands. Inhibitory effect of somatostatin

Abstract

The action of catecholamines and somatostatin on cyclic adenosine 3',5' monophosphate (cyclic AMP) formation in human isolated gastric glands is reported. We show that: (1) there is a beta 2 receptor-mediated stimulation of cyclic AMP production in fundus. Catecholamines act with the order of potencies isoproterenol (ED50 = 50 nmol 1(-1) greater than epinephrine (ED50 = 0.1 mumol 1(-1] greater than norepinephrine (ED50 = 5 mumol 1(-1]. Their action is completely reversed by propranolol at doses 10(3) times lower than practolol, while unaffected by phentolamine; (2) isoproterenol and Vasoactive Intestinal Peptide (VIP) have additive effects on cyclic AMP in fundic glands whereas no additivity is observed between histamine and isoproterenol; this, together with the absence of catecholamine effect in antral glands, suggests that the beta 2 receptor is located on parietal cells; (3) somatostatin (1 mumol 1(-1] non-competitively inhibits the stimulation by catecholamines but does not affect VIP and histamine stimulations. These results suggest a physiological stimulatory effect of catecholamines on gastric acid secretion in man, through a beta 2 receptor coupled to the cyclic AMP system, regulated by somatostatin.

Somatostatin inhibits VIP‐ and isoproterenol‐stimulated cyclic AMP accumulation in rat prostatic epithelial cells

“…The characteristics of the inhibition by somatostatin of the VIP-and B-adrenergic-induced cyclic AMP accumulation in rat prostatic epithelial cells are similar to those previously described in other systems such as pituitary tumor cells [7] and gastric epithelial glands [8]. Somatostatin was without effect on basal cyclic AMP levels whereas VIP and isoproterenol exerted a permissive role upon the somatostatin inhibitory response.…”

“…Recent immunohistochemical studies have demonstrated the presence of somatostatin endocrine-paracrine cells in the prostate gland [5,6] thus making possible a physiological involve-Correspondence address: J.C. Prieto, Departamento de Bioquimica y Biologia Molecular, Universidad de Alcal~t de Henares, Madrid, Spain ment of this hormone in prostatic growth and functions. Somatostatin is a well known inhibitor of cyclic AMP synthesis stimulated by a number of agents including VIP [7] and catecholamines [8] in other tissues. The present study examined the action of somatostatin, both alone or in combination with VIP and the /Y-adrenergic agonist isoproterenol, upon cyclic AMP accumulation in isolated epithelial cells of rat ventral prostate.…”

“…Somatostatin is a well known inhibitor of cyclic AMP synthesis stimulated by a number of agents including VIP [7] and catecholamines [8] in other tissues. The present study examined the action of somatostatin, both alone or in combination with VIP and the /Y-adrenergic agonist isoproterenol, upon cyclic AMP accumulation in isolated epithelial cells of rat ventral prostate.…”

Pharmacological control of the human gastric histamine H2 receptor by famotidine: comparison with H1, H2 and H3 receptor agonists and antagonists

“…Famotidine was shown here to be a very potent and selective histamine H2 receptor antagonist in human fundic membranes. The thiazole derivative did not interfere with the activation by forskolin of the Gs and catalytic subunits of adenylate cyclase as well as VIP, 8 2 adrenergic and PGE2 receptors that are positively coupled to the membrane-bound enzyme [lo, 25,27,36,371. In uitro, famotidine has no action on PI, histamine HI and cholinergic muscarinic receptors in the guinea-pig atria [54], further indicating the selectivity of the drug for the H2 receptor.…”

“…As shown in Fig. 2, the HZ receptor antagonist In contrast, famotidine has no action on other effectors of the adenylate cyclase system in human fundic membranes, including forskolin and membrane receptors sensitive to isoproterenol &-type adrenergic receptor), PGEz and vasoactive intestinal peptide VIP [8,25,27,36,371.…”