The role of calcium and cyclic nucleotides in alpha-amylase release from slices of rat parotid: studies with the divalent cation ionophore A-23187.
The divalent cation ionophore A-23187 caused a Ca-2+-dependent increase in alpha-amylase release from slices of rat parotid gland. The effect of A-23187 on alpha-amylase release was not caused by release of endogenous agonists since l-propranolol, phentolamine, and atropine had no effect. The magnitude of alpha-amylase release caused by A-23187 was small compared to the effect of isoproterenol. In this respect it more closely resembles the action of cholinergic and alpha-adrenergic agonists on alpha-amylase release. A-23187 inhibited the increase in the level of parotid adenosine 3,5'-monophosphate caused by isoprotrenol. The inhibitory effect required incubation of the slices with the ionophore before the addition of isoproterenol. The ionophore also caused a Ca-2+-dependent increase in the level of guanosine 3',5'-monophosphate (cyclic GMP). Theophylline enhanced the effect of A-23187 on the level of cyclic GMP. These results emphasize the role of Ca-2+ in the regulation of parotid cyclic nucleotide levels. Since the effects of the ionophore depended on the presence of Ca-2+, it is possible that some of the effects of agonists on parotid gland physiology are secondary to an action on intracellular Ca-2+ distribution.
D000681:Amylases / Q000378:metabolism*; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000494:pharmacology*; D002217:Carbachol / Q000494:pharmacology; D000242:Cyclic AMP / Q000032:analysis*; D006152:Cyclic GMP / Q000032:analysis*; D004347:Drug Interactions; D005260:Female; D007545:Isoproterenol / Q000494:pharmacology; D010306:Parotid Gland / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D010646:Phentolamine / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D013268:Stimulation, Chemical; D013806:Theophylline / Q000494:pharmacology; D013997:Time Factors
D001285:Atropine; D002217:Carbachol; D011433:Propranolol; D013806:Theophylline; D000242:Cyclic AMP; D000681:Amylases; D006152:Cyclic GMP; D007545:Isoproterenol; D011188:Potassium; D002118:Calcium; D010646:Phentolamine