POSSIBLE ROLE OF CALCIUM IN THE CARDIOVASCULAR EFFECTS OF PROLONGED ADMINISTRATION OF GAMMA-HCH (LINDANE) IN RATS

Gamma-HCH (lindane) administered for long durations is reported to cau se toxic cardiovascular effects. Present study was carried out to asse ss the changes in cardiovascular activity and cellular calcium homeost atic mechanisms in rats administered 3 mg kg(-1) day(-1) of gamma-HCH p.o. for 6 weeks. The changes in electrocardiogram were marked by a de crease in R-R interval and the amplitude of the P wave by 53% and 50%, respectively. The amplitude of R and T waves was increased by 65% and 58%, respectively. Calcium-45 influx was increased in atrial trabecul ae (33%) and in papillary muscle (10%). The plasma calcium concentrati on was increased (32%) and Ca,K-ATPase activity in heart was decreased (50%). It is suggested on the basis of these findings that cellular c alcium homeostatic mechanisms are involved in the cardiovascular effec ts of gamma-HCH administered chronically in rats.