Abstract
Ischemia followed by reperfusion (I/R) in the presence of polymorphonuclear leukocytes (PMNs) results in a marked cardiac contractile dysfunction. A cell-permeable protein kinase C (PKC) βII peptide inhibitor was used to test the hypothesis that PKC βII inhibition could attenuate PMN-induced cardiac dysfunction by suppression of superoxide production from PMNs and increase NO release from vascular endothelium. The effects of the PKC βII peptide inhibitor were examined in isolated ischemic (20 min) and reperfused (45 min) rat hearts with PMNs. The PKC βII inhibitor (10 μM; n = 7) significantly attenuated PMN-induced cardiac dysfunction compared with I/R hearts (n = 9) receiving PMNs alone in left ventricular developed pressure (LVDP) and the maximal rate of LVDP (+dP/dtmax) cardiac function indices (p < 0.01). The PKC βII inhibitor at 10 μM significantly increased endothelial NO release from a basal value of 1.85 ± 0.18 pmol NO/mg tissue to 3.49 ± 0.62 pmol NO/mg tissue from rat aorta. It also significantly inhibited superoxide release (i.e., absorbance) from N-formyl-l-methionyl-l-leucyl-l-phenylalanine-stimulated rat PMNs from 0.13 ± 0.01 to 0.02 ± 0.004 (p < 0.01) at 10 μM. Histological analysis of the left ventricle of representative rat hearts from each group showed that the PKC βII peptide inhibitor-treated hearts experienced a marked reduction in PMN vascular adherence and infiltration into the postreperfused cardiac tissue compared with I/R + PMN hearts (p < 0.01). These results suggest that the PKC βII peptide inhibitor attenuates PMN-induced post-I/R cardiac contractile dysfunction by increasing endothelial NO release and by inhibiting superoxide release from PMNs.
Footnotes
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This study was supported by the National Heart, Lung, and Blood Institute, the National Institutes of Health Grant R15HL76235-01, and in part by Philadelphia College of Osteopathic Medicine, Department of Pathology, Microbiology, and Immunology, and the Center for the Study of Chronic Diseases of Aging.
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doi:10.1124/jpet.104.082131.
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ABBREVIATIONS: PMN, polymorphonuclear leukocyte; PKC, protein kinase C; I/R, ischemia/reperfusion; RACK-1, receptor for activated C kinase-1; LVDP, left ventricular developed pressure; +dP/dtmax, maximal rate of development of pressure; PBS, phosphate-buffered saline; K-H, Krebs-Henselit; l-NAME, Nω-nitro-l-arginine methyl ester; fMLP, N-formyl-l-methionyl-l-leucyl-l-phenylalanine, SOD, superoxide dismutase.
- Received December 10, 2004.
- Accepted April 4, 2005.
- The American Society for Pharmacology and Experimental Therapeutics
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