Interaction of cA-kinase and cG-kinase in mediating relaxation of dispersed smooth muscle cells.
The signaling pathways mediating relaxation by vasoactive intestinal peptide (VIP), peptide histidine-isoleucine amide (PHI), isoproterenol (ISO), and sodium nitroprusside (SNP) were examined in dispersed rabbit and guinea pig gastric muscle cells. In rabbit muscle cells, SNP stimulated only guanosine 3',5'-cyclic monophosphate (cGMP) and cGMP-dependent protein kinase (cG-kinase) activity; VIP stimulated adenosine 3',5'-cyclic monophosphate (cAMP) and cGMP, and both cG-kinase and cAMP-dependent protein kinase (cA-kinase) activities; PHI and ISO stimulated only cAMP and cA-kinase activity, and at higher concentrations, cross-activated cG-kinase. All four agents elicited concentration-dependent relaxation. N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H-89; 1 microM) selectively inhibited cA-kinase activity and abolished relaxation when only cA-kinase was elevated. 8R,9S, 11S-(-)-9-methoxy-carbamyl-8-methyl-2,3,9,10-tetrahydro-8,11-epoxy- 1H,8H,11H-2,7b,11a-trizadibenzo-(a,g)-cy-cloocta-(c,d,e)- trinden-1-one (KT-5823; 1 microM) selectively inhibited cG-kinase activity and abolished relaxation when only cG-kinase was elevated. When both kinases were elevated, H-89 and KT-5823 partially inhibited relaxation and abolished relaxation in combination. In permeabilized guinea pig and rabbit muscle cells, all agents elicited relaxation and inhibited inositol 1,4,5-trisphosphate (IP3)-induced Ca2+ release. Both functions were inhibited in parallel fashion by protein kinase inhibitor PKI(6-22) and by KT-5823. We conclude that cA-kinase and cG-kinase act separately and in concert to inhibit IP3-dependent Ca2+ release and induce relaxation.
Department of Physiology, Medical College of Virginia, Richmond 23298-0711.
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Murthy
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Makhlouf
D000818:Animals; D002118:Calcium / Q000378:metabolism; D000242:Cyclic AMP / Q000819:agonists; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D006152:Cyclic GMP / Q000819:agonists; D017869:Cyclic GMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D004789:Enzyme Activation; D006168:Guinea Pigs; D066298:In Vitro Techniques; D015544:Inositol 1,4,5-Trisphosphate / Q000502:physiology; D009126:Muscle Relaxation / Q000502:physiology*; D009130:Muscle, Smooth / Q000166:cytology / Q000502:physiology*; D009467:Neuromuscular Depolarizing Agents; D011817:Rabbits
D009467:Neuromuscular Depolarizing Agents; D015544:Inositol 1,4,5-Trisphosphate; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D017869:Cyclic GMP-Dependent Protein Kinases; D006152:Cyclic GMP; D002118:Calcium