Cav1.2 calcium channel is glutathionylated during oxidative stress in guinea pig and ischemic human heart

Glutathionylation as a posttranslational modification of proteins is becoming increasingly recognized, but its role in many diseases has not been demonstrated. Oxidative stress and alterations in calcium homeostasis are associated with the development of cardiac hypertrophy. Because the cardiac L-type Ca2+ channel can be persistently activated after exposure to H2O2, the aim of this study was to determine whether alterations in channel function were associated with glutathionylation of the α1C subunit (Cav1.2) channel protein. Immunoblot analysis indicated that Cav1.2 protein is significantly glutathionylated after exposure to H2O2 and glutathione in vitro and after ischemia-reperfusion injury. L-type Ca2+ channel macroscopic current and intracellular calcium were significantly increased in myocytes after exposure to oxidized glutathione and reversed by glutaredoxin. The increase in current correlated with an increase in open probability of the channel assessed as changes in single-channel activity after exposing the human long N-terminal Cav1.2 to H2O2 or oxidized glutathione. We also demonstrate that the Cav1.2 channel is significantly glutathionylated in ischemic human heart. We conclude that oxidative stress is associated with an increase in glutathionylation of the Cav1.2 channel protein. We suggest that the associated constitutive activity contributes to the development of pathology in ischemic heart disease.