Ca(v)1.2 calcium channel is glutathionylated during oxidative stress in guinea pig and ischemic human heart

Abstract

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 Ca(2+) channel can be persistently activated after exposure to H(2)O(2), the aim of this study was to determine whether alterations in channel function were associated with glutathionylation of the α(1C) subunit (Ca(v)1.2) channel protein. Immunoblot analysis indicated that Ca(v)1.2 protein is significantly glutathionylated after exposure to H(2)O(2) and glutathione in vitro and after ischemia-reperfusion injury. L-type Ca(2+) 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 Ca(v)1.2 to H(2)O(2) or oxidized glutathione. We also demonstrate that the Ca(v)1.2 channel is significantly glutathionylated in ischemic human heart. We conclude that oxidative stress is associated with an increase in glutathionylation of the Ca(v)1.2 channel protein. We suggest that the associated constitutive activity contributes to the development of pathology in ischemic heart disease.