title: Effect of temperature on muscarinic cholinoceptor-mediated phosphoinositide metabolism and tension generation in bovine tracheal smooth muscle.
abstract: The effect of decreased temperature on phosphoinositide metabolism was studied in flurbiprofen pretreated bovine tracheal smooth muscle (BTSM) by investigating the consequences of cooling on muscarinic-cholinoceptor-mediated [3H]inositol phosphate ([3H]InsP) and inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) accumulation, basal phosphoinositidase C (PIC) activity and airways smooth muscle (ASM) tone. Cooling of [3H]Ins labelled BTSM slices from 37 degrees C to 27 degrees C for 20 min prior to the addition of agonist caused a substantial (73.0 +/- 2.5%) inhibition of carbachol (100 microM, 30 min)-stimulated [3H]InsP accumulation compared to values measured at 37 degrees C. The degree of inhibition of [3H]InsP accumulation was similar at all agonist time points (2-30 min) studied. In parallel experiments, cooling of unlabelled BTSM slices from 37 degrees C to 27 degrees C resulted in a 34% reduction in basal Ins(1,4,5)P3 mass (37 degrees C, 13.1 +/- 0.6 pmol mg-1 protein; 27 degrees C, 8.9 +/- 0.9 pmol mg-1 protein; P < 0.02) and markedly attenuated carbachol (100 microM)-stimulated increases in Ins(1,4,5)P3 accumulation. Basal PIC activity in the soluble fraction of BTSM homogenates, measured using a [3H]phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) /deoxycholate assay system, was also significantly lower at 27 degrees C compared to 37 degrees C (initial velocities of PtdIns(4,5)P2 hydrolysis of 853 +/- 167 (37 degrees C) and 418 +/- 119 (27 degrees C) pmol min-1 ml-1 (1/400 diluted) BTSM cytosol; p < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Cell Physiology and Pharmacology, University of Leicester, UK.
authors.forename: E R
authors.initials: ER
authors.lastname: Chilvers
authors.forename: M A
authors.initials: MA
authors.lastname: Giembycz
authors.forename: R A
authors.initials: RA
authors.lastname: Challiss
authors.forename: G J
authors.initials: GJ
authors.lastname: Offer
authors.forename: S R
authors.initials: SR
authors.lastname: Nahorski
mesh_terms: D008455:(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethylammonium Chloride / Q000494:pharmacology; D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D002417:Cattle; D003080:Cold Temperature; D006868:Hydrolysis; D009119:Muscle Contraction / Q000502:physiology*; D009130:Muscle, Smooth / Q000378:metabolism / Q000502:physiology*; D010716:Phosphatidylinositols / Q000378:metabolism*; D011976:Receptors, Muscarinic / Q000378:metabolism / Q000502:physiology*; D013997:Time Factors; D014132:Trachea / Q000378:metabolism / Q000502:physiology*
chemical_list: D010716:Phosphatidylinositols; D011976:Receptors, Muscarinic; D008455:(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethylammonium Chloride; D002217:Carbachol