Blockade of L-type Ca2+ channels suppresses activation of calcineurin and development of right ventricle cardiac hypertrophy induced by chronic hypoxia

AIM: To study the role of calcineurin in the progression of right ventricle cardiac hypertrophy in the chronic hypoxia rats and examine the effect of Ca²⁺ channel blockers on the activation of calcineurin. METHODS: Sixty rats were divided into three groups: treatment group with amlodipine besylate ablets, chronic hypoxia group, normal control group with normal oxygen. The rats in treatment group and chronic hypoxia group were exposed to normobaric chronic hypoxia(10±0.5)% O₂ for 21 days. All hearts were removed immediately after dissection for further investigation. RESULTS: (1)The RV/(LV+S),RV/BW were significantly higher in hypoxia group than that of control group and treatment group(P<0.01,respectively); (2) Right ventricular cardiomyocytes Ca²⁺]_i in treatment group were significantly higher than that of control group and lower that that of hypoxia group(P<0.01,respectively); (3) The activity of calcineurin of the heart in hypoxia group were significantly increased when compared with control group. Amlodipine besylate ablets apparently suppressed the activity of calcineurin(P<0.01). CONCLUSION: Calcineurin possibly plays a role in the progression of right ventricle cardiac hypertrophy in the chronic hypoxia rats;Blockade of L-type Ca²⁺ channels with amlodipine besylate ablets effectively prevents its development possibly by inhibition of calcium inflow and suppression of the calcineurin activity.