Purpose The present study aims to investigate the molecular basis of L-type voltage dependent calcium channel (LVDCC) in adult and aged canine.
Methods The action potential duration (APD90), amplitude of action potential plateau, ICa-L peak current density were of LVDCC, recorded by patch clamp technique. The mRNA gene and protein expression levels of α1c subunit (CaV1.2), sarcoplasmic reticulum Ca2+-ATPase (SECRA2), Calpain-I, ryanodine receptor (RyR2) were detected by semi-quantitative RT-PCR.
Results ICa-L peak current density was (−14.04±0.82 pA/pF), in adult group compared with (−8.11±0.54 pA/pF, p<0.05) in the aged group and action potential duration to 90% repolarisation (APD90) of aged group was significantly decreased. The mRNA gene expression levels of CaV1.2 was significantly lower in the aged dogs (0.9±0.35) than in the adult dogs (2.38±0.4, p<0.05), The mRNA gene expression levels of RYR2 was significantly higher in the aged dogs (4.39±4.68) than in the adult dogs (1.49±1.69, p<0.05). There were not significantly different gene expression levels of SECRA2 and calpain I in two groups; The protein expression levels of CaV1.2 were significantly lower in the aged dogs than in the adult dogs (0.13±0.10 vs 0.29±0.12, p<0.05), The protein expression levels of RYR2 was significantly higher in the aged dogs than in the adult dogs (0.18±0.21 vs 0.08±0.36, p<0.05), There were not significantly different protein expression levels of SECRA2 and Calpain I in two groups.
Conclusion These data suggest that the change of mRNA and protein expression of CaV1.2 and RYR2 of LVDCC may serve as the molecular basis of ICa-L remodeling respectively in aged dogs. This plays an important role in the predisposition to developing atrial fibrillation (AF) due to ageing.