RESUMO
The present study aimed to investigate the protective effect of concurrent administration of methylene blue [MB] [1mg/kg, i.p. day] on heart and blood under repeated CO intoxication [1% for 4 minutes / day] for a period up to 30 days in female adult albino rats. Animals were divided into four groups. First group is the control group where the animals admistered saline and breathed natural air. Methylene blue group, where the animals received methylene blue [MB] [1mg/kg/day, i.p]. Carbon monoxide group [CO] that inhaled carbon monoxide [CO, 1%] for 4 minutes day in a closed chamber. Carbon monoxide plus methylene group where the animals pretreated with MB followed by CO inhalation at the aforementioned doses. A group of eight rats from each group was sacrificed at time intervals of 10, 20 and 30 days. Levels of methemoglobin [met Hb] and gas analysis [P02 and PCO[2]] were measured in arterial blood. Superoxide dismutase [SOD], reduced glutathione [GSH], malondialdehyde [MDA] as oxidative stress parameters and adenosine triphosphate [AlP] content were measured in heart and blood serum. Carbon monoxide increased PCO[2] and decreased P02 levels, decreased the ATP content and increased the level of met Hb in blood in comparison to control. Moreover, CO-treated animals showed increased levels of MDA and decreased levels of GSH and SOD in blood and heart tissues. Methylene blue pretreatment significantly minimized the adverse effect of CO and restored normal levels of tested blood gases, cleans the hemoglobin [decreased met Hb], normalized the levels of ATP, GSH. The study suggests that carbon monoxide induced its harmful effects by poisoning hemoglobin and /or induction of oxidative stress. The restorative effects of methylene blue on the physiological functions might be due to the potential of MB as antioxidant and to replace CO in Rb molecule