Agonist-induced inositol phosphate responses in bovine airway submucosal glands.
Agonist-induced inositol phosphate responses were investigated in bovine airway submucosal glands prelabeled with [3H]inositol. The agents used included muscarinic, adrenergic, and histaminergic agonists and NaF as a direct stimulant of phosphoinositidase C. Carbachol (1 microM-1 mM) produced concentration-related [3H]-inositol phosphate formation [maximal response 7.3-fold, half-maximal effective concentration (EC50) 47 microM]. This response was inhibited by atropine [affinity constant (Ka) 1.5 x 10(9) M-1], suggesting the involvement of a muscarinic receptor. Histamine (EC50 66 microM, 2.4-fold stimulation) and norepinephrine (EC50 28 microM, 2.7-fold stimulation) also produced concentration-dependent [3H]inositol phosphate responses. The response to histamine was inhibited by mepyramine (Ka 1.9 x 10(8) M-1), and the response to norepinephrine was inhibited by phentolamine (Ka 1.3 x 10(8) M-1) and prazosin (Ka 2.3 x 10(8) M-1), indicating the involvement of H1 and alpha 1-receptors, respectively, in these responses. NaF also produced concentration-dependent [3H]inositol phosphate formation compatible with the involvement of a G protein in this response. These results demonstrate that a range of secretagogues induce inositol phosphate responses in bovine airway submucosal glands. This response may underlie stimulus response coupling in this tissue.
Hall
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IP
Department of Therapeutics, University Hospital of Nottingham, United Kingdom.
D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology*; D002417:Cattle; D006632:Histamine / Q000494:pharmacology*; D066298:In Vitro Techniques; D007294:Inositol / Q000378:metabolism; D007295:Inositol Phosphates / Q000378:metabolism*; D007375:Interleukin-1 / Q000494:pharmacology; D007700:Kinetics; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism; D009638:Norepinephrine / Q000494:pharmacology*; D011738:Pyrilamine / Q000494:pharmacology; D012969:Sodium Fluoride / Q000494:pharmacology; D014132:Trachea / Q000187:drug effects / Q000378:metabolism*; D014316:Tritium
D007295:Inositol Phosphates; D007375:Interleukin-1; D014316:Tritium; D007294:Inositol; D006632:Histamine; D002217:Carbachol; D012969:Sodium Fluoride; D011738:Pyrilamine; D001920:Bradykinin; D009638:Norepinephrine