Adrenergic regulation of formation of inositol phosphates in rat submandibular acini.
Formation of inositol phosphates in response to adrenergic secretagogues was studied in rat submandibular acini labelled with myo-[2-3H]inositol. Noradrenaline rapidly (within 5 s) increased radioactivity incorporated into inositol 1,4,5-trisphosphate and inositol tetrakisphosphate, with less rapid (within 1 min) increases in inositol 1,3,4-trisphosphate being observed. Inositol polyphosphate formation was less sensitive to noradrenaline than was stimulation of mucin secretion and was mediated by stimulation of alpha- but not beta-adrenergic receptors. The beta-adrenergic agonist isoproterenol, which is a potent stimulator of mucin secretion [McPherson & Dormer (1984) Biochem. J. 224, 473-481] did not increase formation of inositol mono-, bis- or polyphosphates during a 15 min incubation. The results suggest that inositol phosphates do not mediate beta-adrenergic stimulation of mucin secretion in rat submandibular acini. In addition, rat submandibular acinar cells contain a Ca2+ pool which can be mobilized by isoproterenol [McPherson & Dormer (1984) Biochem. J. 224, 473-481], without involvement of inositol polyphosphates as second messengers.
D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D007295:Inositol Phosphates / Q000378:metabolism*; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology*; D010646:Phentolamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013363:Submandibular Gland / Q000187:drug effects / Q000378:metabolism*; D013403:Sugar Phosphates / Q000378:metabolism*; D013997:Time Factors
D007295:Inositol Phosphates; D013403:Sugar Phosphates; D011433:Propranolol; D007545:Isoproterenol; D009638:Norepinephrine; D010646:Phentolamine