Effect of urocortin on L-type calcium currents in adult rat ventricular myocytes.

The newly isolated peptide, urocortin (UCN) has been found to have potent cardioprotective effects. In order to investigate the effect of UCN on L-type calcium currents (ICa,L), exploring the mechanisms of UCN’s cardioprotective effects, we directly measured the ICa,L in the adult rat cardiac myocytes exposed to UCN using standard whole-cell patch-clamp recording technique. Our results showed that UCN exerted decreasing effects on the ICa,L of the single adult rat cardiac myocytes. The current density was inhibited by about 35% after exposure of the cells to UCN (0.1μmolL−1) for 10min, from the control value of 7.19 ± 1.44pA/pF to 4.74 ± 0.75pA/pF (n = 5, P < 0.05). This ICa,L-inhibiting action of UCN was concentration dependent. Moreover, no frequency dependence of UCN effects on ICa,L was observed. In combination with previous reports, our results suggest that there might be a close relationship between the cardioprotective effects of UCN and L-type calcium channels.