期刊
BASIC RESEARCH IN CARDIOLOGY
卷 101, 期 4, 页码 311-318出版社
SPRINGER HEIDELBERG
DOI: 10.1007/s00395-006-0587-2
关键词
atrial natriuretic peptide; guanylyl cyclase; ischemia/reperfusion; mK(ATP) channels; protein kinase G
We investigated whether atrial natriuretic peptide (ANP) given just prior to reperfusion reduces infarction in rabbit hearts and whether protection is related to activation of protein kinase G (PKG). Isolated rabbit hearts were subjected to a 30-min period of regional ischemia; treated hearts received a 20-min infusion of ANP (0.1 mu M) starting 5 min before 2 h of reperfusion. ANP infusion decreased infarction from 31.5 +/- 2.4% of the risk zone in untreated hearts to 12.5 +/- 2.0% (P < 0.001). To explore mechanisms of protection ischemic hearts were treated simultaneously with ANP and isatin, a blocker of the natriuretic peptide receptor, shortly before reperfusion. ANP's protective effect was aborted (36.8 +/- 2.9% infarction). There is no acceptable blocker of protein kinase G that can be used in intact organs. However, 8-(4-chlorophenylthio)-guanosine 3', 5'-cyclic monophosphate (10 mu M), a cell-permeable cGMP analog that directly activates PKG, was infused from 5 min before to 15 min after reperfusion. The PKG activator mimicked ANP's protection with only 18.2 +/- 3.6% infarction (P < 0.001). 5-Hydroxyde-canoate (5-HD), a putative mitochondrial K-ATP channel (mK(ATP)) inhibitor, abrogated ANP's protection (34.4 +/- 2.6% infarction). Unexpectedly, 1H-[1,2,4]oxadiazole- [4,3-a]quinoxalin-1-one (ODQ), a blocker of soluble guanylyl cyclase also prevented ANP's infarct-sparing effect. It is unclear whether this observation implicated participation of soluble guanylyl cyclase in the mechanism or simply a lack of selectivity of ODQ. Finally the reperfusion injury salvage kinases (RISK), phosphatidylinositol 3-kinase and extracellular signal-regulated kinase, were implicated in ANP's mechanism since either wortmannin or PD98059 infused at reperfusion prevented ANP's infarct-sparing effect. ANP administered just prior to reperfusion protects hearts against infarction, likely by activation of PKG, opening of mK(ATP), and stimulation of downstream kinases.
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