Adenylyl cyclase isoforms and vasopressin enhancement of agonist-stimulated cAMP in vascular smooth muscle cells.
The influence of arginine vasopressin (AVP) on agonist-stimulated adenosine 3',5'-cyclic monophosphate (cAMP) accumulation was investigated in vascular smooth muscle cells (VSMC) cultured from rat thoracic aorta. Incubation of VSMC with AVP for 60 s produced a 2- to 2.5-fold enhancement of isoproterenol-induced cAMP formation. AVP also increased cAMP stimulation by the prostaglandin I2 analogue iloprost. The effect of AVP to enhance agonist-stimulated cAMP formation was completely inhibited in cells pretreated with a selective antagonist of V1 vasopressin receptors but was not affected by blockade of V2 receptors. Inhibition of protein kinase C activation failed to alter the action of AVP to potentiate cAMP stimulation, but treatment of cells with calmodulin antagonists significantly attenuated this effect of the peptide. Moreover, depletion of Ca2+ stores with thapsigargin decreased AVP enhancement of isoproterenol-stimulated cAMP by > 70%. The action of AVP to increase cAMP stimulation was also demonstrated in freshly isolated strips of rat aorta where treatment with peptide produced a twofold increase in isoproterenol-stimulated cAMP formation. RNA blot analysis indicated expression in VSMC of mRNA encoding type III adenylyl cyclase, a Ca(2+)-calmodulin-sensitive isoform of the effector. Furthermore, when detergent-solubilized membrane extract was subjected to calmodulin affinity chromatography, a peak of adenylyl cyclase activity was identified which had affinity for calmodulin matrix in the presence of Ca2+. The results indicate that AVP activates V1 receptors in VSMC to enhance agonist-stimulated cAMP formation by a Ca(2+)-calmodulin-dependent mechanism and suggest that type III adenylyl cyclase may provide a focal point in the VSMC for cross talk between constrictor and dilator pathways.
Zhang
J
J
Department of Cell and Molecular Pharmacology, Medical University of South Carolina, Charleston 29425, USA.
Sato
M
M
Duzic
E
E
Kubalak
S W
SW
Lanier
S M
SM
Webb
J G
JG
D000262:Adenylyl Cyclases / Q000378:metabolism*; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D065092:Antidiuretic Hormone Receptor Antagonists; D001011:Aorta / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D001127:Arginine Vasopressin / Q000494:pharmacology*; D002118:Calcium / Q000502:physiology; D002147:Calmodulin / Q000502:physiology; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000819:agonists* / Q000378:metabolism*; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000378:metabolism*; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D011493:Protein Kinase C / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley
D065092:Antidiuretic Hormone Receptor Antagonists; D002147:Calmodulin; D007527:Isoenzymes; D000804:Angiotensin II; D001127:Arginine Vasopressin; D000242:Cyclic AMP; D011493:Protein Kinase C; D000262:Adenylyl Cyclases; D007545:Isoproterenol; D002118:Calcium