Modulation of L-type calcium current in rat cardiac myocytes by sulfur dioxide derivatives

Abstract

The effects of sulfur dioxide (SO 2) derivatives (bisulfite and sulfite, 1:3 M/M) on voltage-dependent L-type calcium current ( I Ca,L) in isolated rat ventricular myocytes were studied using the whole cell patch-clamp technique. SO 2 derivatives increased I Ca,L in a concentration-dependent manner. SO 2 derivatives shifted both the steady-state activation and the inactivation curves of I Ca,L to more positive potentials, the effect on the latter being more pronounced. SO 2 derivatives markedly accelerated the recovery of I Ca,L from inactivation. SO 2 derivatives also significantly shortened the fast and slow time constants of inactivation. These results suggested that SO 2 inhalation might cause cardiac myocyte injury through increasing intracellular calcium via voltage-gated calcium channels.