Role of nitric oxide and protein kinase C in the tachyphylaxis to vasopressin in rat aortic rings.
The contribution of endothelium-derived mediators and protein kinase C in the tachyphylaxis to arginine vasopressin (AVP) was assessed in the rat aorta. Endothelium-intact (E+) and denuded rings (E-) obtained from the rat thoracic aorta were exposed to three administrations of a supramaximal concentration of AVP (100 nM), lasting 20 min and 45 min apart. N-Omega-nitro-L-arginine (NNLA), a non-selective inhibitor of all isoforms of NO synthase, and AMT, a selective inhibitor for the inducible (iNOS) and neuronal (nNOS) isoforms, diminished the tachyphylaxis to AVP significantly in both E+ and in E- rings. No iNOS could be detected by Western blots in freshly isolated rings or in rings exposed to AVP, despite a strong signal in rings isolated from LPS-treated rats, while nNOS could be constitutively detected. Inhibition of prostaglandins or epoxyeicosatrienoic acids (EETs) synthesis by diclofenac or clotrimazole, respectively, had no effect on tachyphylaxis while combination of these agents diminished tachyphylaxis in E+ only. Combination of NNLA, diclofenac and clotrimazole blocked completely the tachyphylaxis. Inhibition of PKC by either chelerythrine or bisindolylmaleimide I-HCl (BisI) led to a significant diminution of AVP tachyphylaxis only in E-. Activation of PKC with phorbol-12-myristate-13-acetate (PMA) simulated tachyphylaxis to AVP in E- only, effect blocked by the NO donor, SNP. In conclusion, NO produced from constitutive nNOS present in vascular smooth muscle cells participates in tachyphylaxis to AVP. PKC is involved in this tachyphylaxis only in E- rings, the presence of NO probably diminishing the effects of this kinase.
Faculté de Pharmacie, Université de Montréal, C.P. 6128, Succursale centre-ville, Montréal, QC, Canada H3C 3J7.
Christine
C
Hamel
Esther
E
Millette
Daniel
D
Lamontagne
D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects; D001127:Arginine Vasopressin / Q000494:pharmacology; D001685:Biological Factors / Q000494:pharmacology; D015153:Blotting, Western; D004730:Endothelium, Vascular / Q000502:physiology; D020536:Enzyme Activators / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066298:In Vitro Techniques; D008070:Lipopolysaccharides / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; D019335:Nitroarginine / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D011453:Prostaglandins / Q000502:physiology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017483:Receptors, Vasopressin / Q000187:drug effects; D013618:Tachyphylaxis / Q000502:physiology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014667:Vasopressins / Q000494:pharmacology*
D001685:Biological Factors; D020536:Enzyme Activators; D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; D009419:Nerve Tissue Proteins; D011453:Prostaglandins; D017483:Receptors, Vasopressin; D014662:Vasoconstrictor Agents; C067410:endothelium-dependent hyperpolarization factor; D014667:Vasopressins; D001127:Arginine Vasopressin; D010656:Phenylephrine; D019335:Nitroarginine; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; C496322:Nos1 protein, rat; C496318:Nos2 protein, rat; D011493:Protein Kinase C