The protective effect of calcitonin gene-related peptide (CGRP)-induced preconditioning on myocardial injury due to adriamycin was studied in the isolated perfused rat heart. Adriamycin (100 and 200 (mol / L) caused a gradual decrease in coronary flow (CF) and cardiac function (LVP and LV dp/dtmax), and an increase in the level of MDA. Pretreatment with CGRP at the concentration of 5 nmol/L for 5 min markedly reduced the attenuation of CF and cardiac function and inhibited the elevation of MDA content induced by adriamycin. The findings suggest that the pretreatment with CGRP possesses a protection against myocardial injury elicited by adriamycin. The present results also suggest that the protection of CGRP may be related to a reduction in lipid peroxidation.
The main purpose of this study was to investigate the protective actions of captopril and cicaprost on changes of membrane fluidity of cultured neonatal rat myocardial cells exposed to anoxia and sugar deprivation.Lipid peroxidation level estimated by determining the thiobarbituric acid reactive substance(TBARS)content and lactate dehydrogenase(LDH)released in culture medium was also observed in order to examine other membrane-related changes due to anoxia.Membrane fluidity was monitored by measuring changes in the steady state fluorescence anisotropy(r_s)by fluorescence spectroscopy.The r_s value,TBARS level and LDH release were significantly increased after 3 h anoxia.Captopril(180 μmol/L),cicaprost(30 nmol/L)and indomethacin(1μmol/L)did not alter r_s, TBARS level and LDH activity of normal cultured neonatal rat myocardial cells.However,both captopril and cicaprost significantly prevented the increases of r_s,TBARS content and LDH release in those cells exposed to anoxia and sugar deprivation.lndomethacin abolished the actions of captopril on TBARS production and LDH release,but maintained its membrane fluidity protection.These results indicate that captopril and cicaprost protect membrane fluidity and lipid peroxidation changes in anoxia- injured myocardial cells.The action mechanism of captopril may be due,in part,to stimulation of prostacyclin synthesis and/or release.
