Effect of didrovaltrate on I-calcium current in rabbit ventricular myocytes

Objective

To investigate the effect of didrovaltrate on L-type calcium current (I_ca-L) in rabbit ventricular myocytes.

Methods

We used the whole cell patch clamp recording technique.

Results

Didrovaltrate at concentrations of 30 μg/L and 100 μg/L significantly decreased peak ICa-L (ICa-Lmax) from (6.01 ± 0.48) pA/pF to (3.45±0.27) pA/pF and (2.16 ± 0.19) pA/pF (42.6% and 64.1%, n=8, P<0.01), respectively. Didrovaltrate shifted upwards the current-voltage curves of ICa-L without changing their active, peak and reverse potentials. Didrovaltrate affected the steady-state inactivation of ICa-L. The half activation potential (V_1/2) was significantly shifted from (−26 ± 2) to (−36 ± 3) mV (n=6, P<0.05), with a significant change in the slope factor (k) (from 8.8 ± 0.8 to 11.1 ± 0.9, n=6, P<0.05). Didrovaltrate did not affect the activation curve.

Conclusion

Didrovaltrate blocks ICa-L in a concentration-dependent manner and probably inhibits ICa-L in its inactive state, which may contribute to its cardiovascular effect.