Augmentation and subsequent attenuation of Ca2+ current due to lipid peroxidation of the membrane caused by t‐butyl hydroperoxide in the rabbit sinoatrial node

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Abstract
Cellular electrophysiological effects of membrane lipid peroxidation by t-butyl hydroperoxide (TBH) were studied in the rabbit sinoatrial (SA) node. Superfusion for 1–5 min with 300 μm TBH caused an initial increase and subsequent decrease in the spontaneous firing frequency of the SA node. Voltage clamp experiments revealed that TBH initially enhanced but later blocked the Ca2+ current. Thus, membrane lipid peroxidation appears to accelerate and then suppress physiological automaticity by causing biphasic changes in the Ca2+ current.