Stimulating effect of alpha-adrenoceptor agonists on isoproterenol-induced amylase release in rat parotid tissue.
Isoproterenol (ISO)-induced amylase release from rat parotid slices was increased by the addition of methoxamine to either a normal or a calcium (Ca)-free medium. The potentiating effect of methoxamine was completely blocked by the addition of phentolamine, irrespective of whether the slices were incubated in the normal or the Ca-free medium; and the effect also disappeared after prolonged preincubation (60 min) of the slices in the Ca-free medium. Both verapamil and procaine reduced methoxamine-induced amylase release, but only verapamil blocked the stimulating effect of methoxamine in the normal medium. ISO-induced accumulation of cyclic AMP in the slices was unaffected by methoxamine or phenylephrine. The results suggest a possibility that the potentiating effect of methoxamine on ISO-induced amylase release may be independent of the presence of extracellular Ca and the increased accumulation of cyclic AMP in the tissue is unnecessary.
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000681:Amylases / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D000242:Cyclic AMP / Q000032:analysis; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D008729:Methoxamine / Q000494:pharmacology; D010306:Parotid Gland / Q000032:analysis / Q000187:drug effects / Q000201:enzymology*; D011343:Procaine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D014700:Verapamil / Q000494:pharmacology
D000316:Adrenergic alpha-Agonists; D011343:Procaine; D014700:Verapamil; D000242:Cyclic AMP; D000681:Amylases; D008729:Methoxamine; D007545:Isoproterenol; D002118:Calcium