ATTENUATION OF MYOCARDIAL INJURY DUE TO OXYGEN-FREE RADICALS (OFR) BYPRETREATMENT WITH OFR OR CALCITONIN-GENE-RELATED PEPTIDE

AIM: To study the cardioprotective effects of oxygen free radicals (OF R) and calcitonin gene-related peptide (CGRP) pretreatment on myocardi al damages due to OFR in isolated perfused rat heart. METHODS: The hea rts were perfused in a Langendorff mode. OFR were generated by electro lysis of Krebs-Henseleit (K-H) solution. RESULTS: OFR pretreatment red uced the impairment of cardiac contractile function, the decrease of c oronary flow and the increase of creatinine kinase (CK) release due to OFR, and the effect exhibited period dependence and cycle-dependence. 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), an inhibitor of protein kinase C, abolished the protection of OFR pretreatment (CK re lease = 110 +/- 7, 215 +/- 23, 169 +/- 14, 240 +/- 30, and 113 +/- 19 kU.L-1 for control, OFR, OFR pretreatment, OFR pretreatment plus H-7, and H-7, respectively). CGRP pretreatment also protected the myocardiu m damages elicited by OFR in isolated perfused rat heart. CONCLUSIONS: OFR or CGRP pretreatment protected myocardium against injury elicited by OFR, and the effect of OFR pretreatment was related to the activat ion of PKC.