Propranolol and verapamil inhibit mRNA expression of RyR2 and SERCA in L-thyroxin-induced rat ventricular hypertrophy

AIM: To study the alteration in the mRNA level of cardiac ryanodine receptor 2 (RyR2) and sarco-endoplasmic reticulum Ca^2+-ATPase (SERCA) in L-thyroxin-induced hypertrophy. METHODS: L-thyroxin (500 g/kg) daily was injected for 10 d. RT-PCR was used to determine mRNA expression. RESULTS: An increase in the relative amount of RyR2 (111%) and SERCA mRNA (65 %) expression was observed in the hypertrophied rats (RyR2:77±11; SERCA: 87±10, n=9) compared with the normal rats (RyR2: 36±10; SERCA: 53±10, n=9). Propranolol was effective to inhibit the increase in RyR2 (51±7) and SERCA (63±13) mRNA expression in hypertrophied rats,respectively. Verapamil also reduced RyR2 (62±5) and SERCA (75±8) mRNA expression. CONCLUSION: Both RyR2 and SERCA mRNA level in L-thyroxin-induced cardiac hypertrophy was over-expressed and propranolol or verapamil inhibited the alteration.