title: Regulation of pulmonary venous tone in response to muscarinic receptor activation.
abstract: We investigated cellular mechanisms that mediate or modulate the vascular response to muscarinic receptor activation (ACh) in pulmonary veins (PV). Isometric tension was measured in isolated canine PV rings with endothelium (E+) and without endothelium (E-). Tension and intracellular Ca(2+) concentration ([Ca(2+)](i)) were measured simultaneously in fura-2-loaded E- PV strips. In the absence of preconstriction, ACh (0.01-10 microM) caused dose-dependent contraction in E+ and E- rings. ACh contraction was potentiated by removing the endothelium or by nitric oxide (NO) synthase inhibition (N-nitro-L-arginine methyl ester, P = 0.001). Cyclooxygenase inhibition (indomethacin) reduced ACh contraction in both E+ and E- PV rings (P = 0.013 and P = 0.037, respectively). ACh contraction was attenuated by inhibitors of voltage-operated Ca(2+) channels (nifedipine, P < 0.001), inositol-1,4,5-trisphosphate (IP(3))-mediated Ca(2+) release (2-aminoethoxydiphenyl borate, P = 0.001), PKC (bisindolylmaleimide I, P = 0.001), Rho-kinase (Y-27632, P = 0.002), and tyrosine kinase (TK; tyrphostin 47, P = 0.015) in E- PV rings. ACh (1 microM) caused a leftward shift in the [Ca(2+)](i)-tension relationship (P = 0.015), i.e., ACh increased myofilament Ca(2+) sensitivity. Inhibition of PKC, Rho-kinase, and TK attenuated the ACh-induced increase in myofilament Ca(2+) sensitivity (P < 0.001, P < 0.001, and P = 0.024, respectively). These findings indicate that in canine PV, ACh contraction is modulated by NO and partially mediated by metabolites of the cyclooxygenase pathway and involves Ca(2+) influx through voltage-operated Ca(2+) channels and IP(3)-mediated Ca(2+) release. In addition, ACh induces increased myofilament Ca(2+) sensitivity, which requires the PKC, Rho-kinase, and TK pathways.
authors.affiliation: Center for Anesthesiology Research, The Cleveland Clinic Foundation, Cleveland, OH 44195, USA
authors.forename: Xueqin
authors.initials: X
authors.lastname: Ding
authors.forename: Paul A
authors.initials: PA
authors.lastname: Murray
mesh_terms: D000109:Acetylcholine / Q000008:administration & dosage / Q000494:pharmacology; D008841:Actin Cytoskeleton / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000502:physiology; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000502:physiology; D066298:In Vitro Techniques; D015544:Inositol 1,4,5-Trisphosphate / Q000502:physiology; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases; D011667:Pulmonary Veins / Q000187:drug effects / Q000502:physiology*; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology; D014661:Vasoconstriction / Q000502:physiology; D014666:Vasomotor System / Q000502:physiology*; D054460:rho-Associated Kinases
chemical_list: D015220:Calcium Channels; D047908:Intracellular Signaling Peptides and Proteins; D011976:Receptors, Muscarinic; D015544:Inositol 1,4,5-Trisphosphate; D011451:Prostaglandin-Endoperoxide Synthases; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D011493:Protein Kinase C; D000109:Acetylcholine; D002118:Calcium