Role of PKC, tyrosine kinases, and Rho kinase in alpha-adrenoreceptor-mediated PASM contraction.
Our objectives were to identify the relative contributions of intracellular free Ca2+ concentration ([Ca2+]i) and myofilament Ca2+ sensitivity in the pulmonary artery smooth muscle (PASM) contractile response to the alpha-adrenoreceptor agonist phenylephrine (PE) and to assess the role of PKC, tyrosine kinases (TK), and Rho kinase (ROK) in that response. Our hypothesis was that multiple signaling pathways are involved in the regulation of [Ca2+]i, myofilament Ca2+ sensitization, and vasomotor tone in response to alpha-adrenoreceptor stimulation of PASM. Simultaneous measurement of [Ca2+]i and isometric tension was performed in isolated canine pulmonary arterial strips loaded with fura 2-AM. PE-induced tension development was due to sarcolemmal Ca2+ influx, Ca2+ release from inositol 1,4,5-trisphosphate-dependent sarcoplasmic reticulum Ca2+ stores, and myofilament Ca2+ sensitization. Inhibition of either PKC or TK partially attenuated the sarcolemmal Ca2+ influx component and the myofilament Ca2+ sensitizing effect of PE. Combined inhibition of PKC and TK did not have an additive attenuating effect on PE-induced Ca2+ sensitization. ROK inhibition slightly decreased [Ca2+]i but completely inhibited myofilament Ca2+ sensitization. These results indicate that PKC and TK activation positively regulate sarcolemmal Ca2+ influx in response to alpha-adrenoreceptor stimulation in PASM but have relatively minor effects on myofilament Ca2+ sensitivity. ROK is the predominant pathway mediating PE-induced myofilament Ca2+ sensitization.
Damron
Derek S
DS
Center for Anesthesiology Research, Division of Anesthesiology and Critical Care Medicine, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA.
Kanaya
Noriaki
N
Homma
Yasuyuki
Y
Kim
Si-Oh
SO
Murray
Paul A
PA
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D004285:Dogs; D066298:In Vitro Techniques; D047908:Intracellular Signaling Peptides and Proteins; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D010656:Phenylephrine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D011494:Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011651:Pulmonary Artery / Q000187:drug effects / Q000502:physiology*; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects / Q000502:physiology*; D015203:Reproducibility of Results; D054460:rho-Associated Kinases
D000316:Adrenergic alpha-Agonists; D047908:Intracellular Signaling Peptides and Proteins; D011942:Receptors, Adrenergic, alpha; D010656:Phenylephrine; D011189:Potassium Chloride; D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases