title: C-peptide exerts cardioprotective effects in myocardial ischemia-reperfusion.
abstract: Ischemia followed by reperfusion in the presence of polymorphonuclear leukocytes (PMNs) results in cardiac dysfunction. C-peptide, a cleavage product of proinsulin to insulin processing, induces nitric oxide (NO)-mediated vasodilation. NO is reported to attenuate cardiac dysfunction caused by PMNs after ischemia-reperfusion (I/R). Therefore, we hypothesized that C-peptide could attenuate PMN-induced cardiac dysfunction. We examined the effects of C-peptide in isolated ischemic (20 min) and reperfused (45 min) rat hearts perfused with PMNs. C-peptide (70 nmol/kg iv) given 4 or 24 h before I/R significantly improved coronary flow (P < 0.05), left ventricular developed pressure (LVDP) (P < 0.01), and the maximal rate of development of LVDP (+dP/dt(max)) compared with I/R hearts obtained from rats given 0.9% NaCl (P < 0.01). N(G)-nitro-L-arginine methyl ester (L-NAME) (50 micromol/l) blocked these cardioprotective effects. In addition, C-peptide significantly reduced cardiac PMN infiltration from 183 +/- 24 PMNs/mm(2) in untreated hearts to 44 +/- 10 and 58 +/- 25 PMNs/mm(2) in hearts from 4- and 24-h C-peptide-treated rats, respectively. Rat PMN adherence to rat superior mesenteric artery exposed to 2 U/ml thrombin was significantly reduced in rats given C-peptide compared with rats given 0.9% NaCl (P < 0.001). Moreover, C-peptide enhanced basal NO release from rat aortic segments. These results provide evidence that C-peptide can significantly attenuate PMN-induced cardiac contractile dysfunction in the isolated perfused rat heart subjected to I/R at least in part via enhanced NO release.
authors.affiliation: Department of Physiology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
authors.forename: L H
authors.initials: LH
authors.lastname: Young
authors.forename: Y
authors.initials: Y
authors.lastname: Ikeda
authors.forename: R
authors.initials: R
authors.lastname: Scalia
authors.forename: A M
authors.initials: AM
authors.lastname: Lefer
mesh_terms: D000818:Animals; D002096:C-Peptide / Q000494:pharmacology*; D003326:Coronary Circulation / Q000187:drug effects; D006321:Heart / Q000187:drug effects* / Q000503:physiopathology; D066298:In Vitro Techniques; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D017202:Myocardial Ischemia / Q000503:physiopathology*; D015428:Myocardial Reperfusion Injury / Q000503:physiopathology*; D009504:Neutrophils / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D002096:C-Peptide