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Information Seminar Paper

Title

CHRONIC EXPOSURE TO ARSENIC -INDUCED DYSFUNCTION IN BAROREFLEX SENSITIVITY (BRS) OF RAT

Writers

YOUSEFVAND NAMDAR

Pages

 Start Page | End Page

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Abstract

 Introduction: Some reports have showed that long term arsenic exposure is closely associated with an increased risk of hypertension, ischemic heart disease, cerebral infarction and atherosclerosis. The arterial baroreflex contributes importantly to the short-term regulation of blood pressure and cardiovascular variability.Methods: I investigated the effects of acute (50µgAs/ml water for 1 day) and chronic exposure (2-3 months) of rats to different concentration (25, 50 and 60µg/ml water) of sodium arsenate in drinking water. In rats anaesthetized with a-chloralose (80mg/kg, I.P) femoral vein was cannulated for injection of drugs. Arterial blood pressure (ABP) was recorded continuously from the catheter in the left femoral artery, using a transducer and strain gauge amplifier, the output was displayed on an oscilloscope. Baroreflex sensitivity (BRS) was measured by injecting varying doses of phenlyephrine (PE) (2.5-40µg/kg) and sodium nitroprosside (SNP) (2.5-20µg/kg) through the femoral vein catheter. The changes in arterial blood pressure (ABP) and associated baroreflex-mediated changes in heart rate (HR) were measured and the ratio of change in heart rate/change in mean arterial pressure was taken as an index of baroreflex sensitivity.Results: The BRS was calculated from MAP-HR relationship during the rise of the MAP induced by varying doses of PE, fell in chronic arsenic exposed rats. This effect was significant in arsenic exposed rats treated with 60µg/ml of sodium arsenate in drinking water for 3 months. The BRS was also calculated from MAP-HR relationship during the fall of the MAP induced by varying doses of SNP, fell in chronic arsenic exposed rats.Conclusion: The chronic exposure to arsenic significantly impaired baroreflex sensitivity.

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