title: Protein kinase C plays an essential role in sildenafil-induced cardioprotection in rabbits.
abstract: Sildenafil citrate (Viagra) is the most widely used pharmacological drug for treating erectile dysfunction in men. It has potent cardioprotective effects against ischemia-reperfusion injury via nitric oxide and opening of mitochondrial ATP-sensitive K(+) channels. We further investigated the role of protein kinase C (PKC)-dependent signaling pathway in sildenafil-induced cardioprotection. Rabbits were treated (orally) with sildenafil citrate (1.4 mg/kg) 30 min before index ischemia for 30 min and reperfusion for 3 h. The PKC inhibitor chelerythrine (5 mg/kg i.v.) was given 5 min before sildenafil. Infarct size (% of risk area) reduced from 33.65 +/- 2.17 in the vehicle (saline) group to 15.07 +/- 0.63 in sildenafil-treated groups, a 45% reduction compared with vehicle (mean +/- SE, P < 0.05). Chelerythrine abolished sildenafil-induced protection, as demonstrated by increase in infarct size to 31.14 +/- 2.4 (P < 0.05). Chelerythrine alone had an infarct size of 33.5 +/- 2.5, which was not significantly different compared with DMSO-treated group (36.8 +/- 1.7, P > 0.05). Western blot analysis demonstrated translocation of PKC-alpha, -, and -delta isoforms from cytosol to membrane after treatment with sildenafil. However, no change in the PKC-beta and -epsilon isoforms was observed. These data provide direct evidence of an essential role of PKC, and potentially PKC-alpha, -, and -delta, in sildenafil-induced cardioprotection in the rabbit heart.
authors.affiliation: Department of Medicine, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA 23298, USA.
authors.forename: Anindita
authors.initials: A
authors.lastname: Das
authors.forename: Ramzi
authors.initials: R
authors.lastname: Ockaili
authors.forename: Fadi
authors.initials: F
authors.lastname: Salloum
authors.forename: Rakesh C
authors.initials: RC
authors.lastname: Kukreja
mesh_terms: D000470:Alkaloids; D000818:Animals; D053119:Benzophenanthridines; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006439:Hemodynamics / Q000187:drug effects; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000502:physiology; D008297:Male; D009203:Myocardial Infarction / Q000201:enzymology* / Q000473:pathology / Q000517:prevention & control*; D010617:Phenanthridines / Q000494:pharmacology; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D010879:Piperazines / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D021381:Protein Transport / Q000187:drug effects; D011687:Purines; D011817:Rabbits; D000068677:Sildenafil Citrate; D013347:Subcellular Fractions / Q000187:drug effects / Q000201:enzymology; D013450:Sulfones
chemical_list: D000470:Alkaloids; D053119:Benzophenanthridines; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D010617:Phenanthridines; D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D000068677:Sildenafil Citrate; C016299:chelerythrine; D011493:Protein Kinase C