Propranolol and bepridil attenuating levothyroxine-induced rat cardiac hypertrophy and mitochondrial Ca2+ Mg (2+) -ATPase activity elevation
Chen, D.D.; Dai, D.Z.; Lu, J.; Zhang, X.K.
Zhongguo Yao Li Xue Bao 17(6): 516-518
1996
ISSN/ISBN: 0253-9756 PMID: 9863145 Document Number: 464727
AIM: To study the effects of propranolol and bepridil on levothyroxine-induced rat cardiac hypertrophy and mitochondrial Ca-2+ Mg-2+-ATPase activity elevation. METHODS: Rat heart hypertrophy was induced by ip levothyroxine 1 mg cntdot kg-1 cntdot d-1 times 10 d. Then rats were treated by ig propranolol (Pro) or bepridil (Bep) 10 mg cntdot kg-1 daily. Ca-2+ Mg-2+-ATPase activity and enzyme kinetic parameters were assayed. RESULTS: The activity and V-max of mitochondrial Ca-2+ Mg-2+ATPase isolated from hypertrophic left ventricle were 25 +- 4 and 35.1 +- 0.8 mu-mol P-i cntdot h-1/mg protein, respectively, those of normal were 6.7 +- 1.8 and 10 +- 4 mu-mol P-i cntdot h-1/mg protein, respectively. Apparent K-m of the hypertrophic group Ca-2+ Mg-2+-ATPase was 0.4 +- 0.12 mmol cntdot L-1 ATP, and that of normal was 0.59 +- 0.22 mmol cntdot L-1 ATP. The total protein quantity of hypertrophic left ventricle was 80 +- 30 mg, and that of normal was 47 +- 9 mg. After treated with Pro or Bep (both 10 mg cntdot kg-1 ig) , the cardiac hypertrophy was attenuated, the enzyme activity and V-max as well as total protein quantity of hypertrophic left ventricle were reduced to normal level, but apparent K-m was not affected. CONCLUSION: Both Pro and Bep prevented the myocardium and its mitochondria from ischemia and overload calcium injury.