Local regulation of L‐type calcium channels by reactive oxygen species

Abstract

Arterial smooth muscle voltage‐dependent L‐type calcium channels can operate in a protein kinase C alpha (PKC alpha)‐dependent, high open probability mode resulting in sites of sustained calcium influx called “persistent calcium sparklets.” However, the molecular mechanisms underlying sustained PKC alpha‐dependent calcium channel activity are poorly understood. Here we tested the hypothesis that reactive oxygen species enhance arterial smooth muscle calcium influx by inducing persistent calcium channel (i.e. sparklet) activity. Consistent with this, oxidant exposure increased arterial wall calcium and tone in pressurized cerebral arteries. Using TIRF microscopy and patch clamp electrophysiology, we found that reactive oxygen species promoted localized persistent L‐type calcium channel activity in isolated arterial myocytes via activation of PKC alpha. Furthermore, we observed that punctate subcellular generation of endogenous reactive oxygen species preceded and co‐localized with persistent L‐type calcium channel activity. Taken together, these data suggest that local oxidative activation of PKC alpha‐dependent L‐type channel calcium influx represents a functionally relevant convergence of oxidant and calcium signaling pathways that contribute to calcium entry and arterial tone. This work is supported by the American Heart Association and the National Institutes of Health.