Role of nitric oxide and protein kinase C in ACh-induced cardioprotection.
We examined the roles of nitric oxide and protein kinase C (PKC) in ACh-produced protection of cultured cardiomyocytes during simulated ischemia and reoxygenation. Cell viability was quantified using propidium iodide in chick embryonic ventricular myocytes. O(2) radicals were quantified using 2',7'-dichlorofluorescin diacetate. After a 10-min infusion of ACh (0.5 or 1 mM) and a 10-min drug-free period, we simulated ischemia for 1 h and reoxygenation for 3 h. ACh reduced cardiocyte death [32 +/- 4%; n = 6 and 23 +/- 4%; n = 7 (P < 0.05)] and attenuated oxidant stress during ischemia and reoxygenation in a concentration-dependent manner compared with controls (47 +/- 4%; n = 8; P < 0.05). The increase in O(2) radicals before simulated ischemia [357 +/- 49; n = 4 and 528 +/- 52; n = 8 vs. 211 +/- 34; n = 8; P < 0.05 (arbitrary units)] was abolished by the specific nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) and was markedly attenuated by N(G)-monomethyl-L-arginine (L-NMMA). L-NAME or L-NMMA blocked the protective effects of ACh, which selectively increased PKC-epsilon isoform activity in the particulate fraction. The PKC inhibitor Gö-6976 had no effect on O(2) radical production before simulated ischemia but it abolished the protection; therefore nitric oxide is a large component of ACh-generated O(2) radicals. Nitric oxide and O(2) radicals activate the PKC-epsilon isoform by which ACh protects against injury.
Liu
H
H
Department of Anesthesia and Critical Care, University of Chicago, Chicago, Illinois 60637, USA.
McPherson
B C
BC
Zhu
X
X
Da Costa
M L
ML
Jeevanandam
V
V
Yao
Z
Z
D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D016923:Cell Death / Q000187:drug effects; D002642:Chick Embryo; D003600:Cytosol / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006321:Heart / Q000187:drug effects* / Q000196:embryology / Q000502:physiology; D009206:Myocardium / Q000166:cytology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000502:physiology; D018384:Oxidative Stress / Q000187:drug effects; D020011:Protective Agents / Q000494:pharmacology*; D011493:Protein Kinase C / Q000502:physiology*
D004791:Enzyme Inhibitors; D020011:Protective Agents; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D011493:Protein Kinase C; D000109:Acetylcholine; D019331:NG-Nitroarginine Methyl Ester