Reference

Interactions between the effects of

Interactions between the effects of .alpha.- and .beta.-adrenoceptor agonists and adenine nucleotides on the membrane potential of cells in guinea pig liver slices. Jenkinson, D. H.; Koller, Karin (Dep. Pharmacol., Univ. Coll. London, London, Engl.). Br. J. Pharmacol., 59(1), 163-75 (English) 1977. CODEN: BJPCBM. DOCUMENT TYPE: Journal CA Section: 3 (Biochemical Interactions) The response of the membrane potential of liver cells to .beta.-agonists (e.g. (-)isoprenaline bitartrate [54750-10-6]) and Na cyclic AMP [33116-15-3] was potentiated by simultaneous application of an .alpha.-agonist. Some of the .alpha.-agonists (e.g. naphazoline-HCl [550-99-2]) were also effective when applied before the .beta.-agonists. Hyperpolarizations produced by Na ADP [1172-42-5] and Na ATP [15237-44-2] (0.1-1.0mM) were not increased after .alpha.-agonist treatment, but ADP and ATP enhanced the response to .beta.-agonists. The interactions between .alpha.- and .beta.-agonists and adenine nucleotides may involve steps subsequent to receptor activation.

Central and peripheral adrenergic mechanisms regulating gastric secretion in the rat

Central and peripheral adrenergic mechanisms regulating gastric secretion in the rat. Yamaguchi, I.; Hiroi, J.; Kumada, S. (Dep. Pharmacol., Fujisawa Pharm. Co. Ltd., Osaka, Japan). J. Pharmacol. Exp. Ther., 203(1), 125-31 (English) 1977. CODEN: JPETAB. DOCUMENT TYPE: Journal CA Section: 1 (Pharmacodynamics) Section cross-reference(s): 13 S.c. injection of sympathomimetic agents reduced gastric secretion in pylorus-ligated rats, and the decreasing order of activity was: dl-isoproterenol-HCl [949-36-0], dl-norepinephrine [138-65-8], naphazoline-HCl [550-99-2], and l-phenylephrine-HCl [61-76-7]. The effect of naphazoline and phenylephrine was antagonized with 4 mg/kg, s.c., of phentolamine, and that of isoproterenol with 4 mg/kg, s.c., of propranolol. Thus, there exist sep. .alpha.- and .beta.-adrenergic receptors which control gastric secretion in the rat. Intracerebroventricular (i.c.v.) injection of the sympathomimetic agents also reduced secretion, naphazoline being the most potent. The ED50 of i.c.v. naphazoline was 12.3 times less than that of s.c. dose. The antisecretory effect of i.c.v. naphazoline was antagonized with i.c.v. phentolamine (0.016 and 0.064 mg/kg), but not with propranolol. These results suggest that naphazoline stimulates central .alpha.-adrenergic receptors which has a tonic inhibiting role in rat gastric secretion. Analogous to the results with naphazoline, i.c.v. phentolamine, but not propranolol, blocked an antisecretory effect of chlorpromazine-HCl [50-53-3]. Phentolamine administered s.c. also reduced the antisecretory activity, but the dose required for the antagonism was 250 times that of i.c.v. phentolamine. An antisecretory effect of imipramine-HCl [113-52-0] was not blocked by phentolamine or propranolol. These results suggest that an activation of central .alpha.-adrenergic receptors is important for the antisecretory effect of chlorpromazine.