Bradykinin-stimulated phosphatidate and 1,2-diacylglycerol accumulation in guinea-pig airway smooth muscle: evidence for regulation 'down-stream' of phospholipases.
Bradykinin-treatment of cultured airway smooth muscle (ASM) induced the formation of [3H]1,2-diacylglycerol ([3H]1,2-DG), [3H]1,3-diacylglycerol ([3H]1,3-DG) and [3H]phosphatidic acid ([3H]PtdOH) in [3H]palmitate-labelled cells and of [3H]choline in [3H]methyl choline-labelled cells. [3H]1,2-DG and [3H]1,3-DG responses were biphasic with an initial transient phase from 0-2 min and a second sustained phase to 10 min. In contrast, [3H]PtdOH accumulation plateaued at 2 min stimulation as did [3H]choline formation. The bradykinin-stimulated [3H]1,2-DG and [3H]PtdOH responses exhibited similar concentration dependencies (EC50 values: [3H]1,2-DG 5.14 +/- 2.82 nM; [3H]1,3-DG 4.95 +/- 1.12 nM; [3H]PtdOH 1.52 +/- 0.82 nM). In contrast, PMA elicited a [3H]PtdOH response, but was without effect upon [3H]DG levels. Bradykinin-induced accumulation of [3H]1,2-DG and [3H]PtdOH was insensitive to blockade by a bradykinin B2-receptor antagonist, NPC567 (40 microM) and the B1-receptor agonist, Des-Arg9-bradykinin, (10 microM) failed to elicit a response. These observations are similar to those obtained previously for bradykinin-stimulated phospholipase D activity in ASM (Pyne S. and Pyne N. J., Br. J. Pharmac. 110, 477-481, 1993). Thus, both bradykinin-stimulated 1,2-DG and PtdOH accumulation may also be regulated via a novel B3-receptor. Bradykinin-stimulated formation of [3H]PtdOH was partially inhibited by butan-1-ol (by 47.25 +/- 12.7%, n = 3) which had no effect upon basal or bradykinin-stimulated levels of [3H]1,2-DG or upon basal [3H]PtdOH.(ABSTRACT TRUNCATED AT 250 WORDS)
Pyne
S
S
Department of Physiology and Pharmacology, University of Strathclyde, Royal College, Glasgow, U.K.
Pyne
N J
NJ
D000818:Animals; D001920:Bradykinin / Q000494:pharmacology*; D065168:Bradykinin Receptor Antagonists; D000440:Butanols / Q000494:pharmacology; D002478:Cells, Cultured; D002794:Choline / Q000378:metabolism; D004075:Diglycerides / Q000378:metabolism*; D015536:Down-Regulation; D006168:Guinea Pigs; D009130:Muscle, Smooth / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010712:Phosphatidic Acids / Q000378:metabolism*; D010739:Phospholipase D / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism; D018002:Receptors, Bradykinin / Q000378:metabolism; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014132:Trachea / Q000187:drug effects / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism*
C011439:1,2-diacylglycerol; D065168:Bradykinin Receptor Antagonists; D000440:Butanols; D004075:Diglycerides; D010712:Phosphatidic Acids; D018002:Receptors, Bradykinin; D011493:Protein Kinase C; D010738:Type C Phospholipases; D010739:Phospholipase D; D002794:Choline; D013755:Tetradecanoylphorbol Acetate; D001920:Bradykinin