Modulation of Ionic Currents in Isolated Type I Cells of the Neonatal Rat Carotid Body by p-Chloromercuribenzenesulfonic Acid

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The sulphydryl reagent, p-chloromercuribenzenesulfonic acid (PCMB S), irreversible excites the carotid body in vivo. We tested the effects of PCMBS on ionic currents in isolated type I cells, using the whole-cell patch-clamp technique. PCMBS selectively and irreversibly inhibited the Ca2+-activated K+ current (IKca) in a dose-dependent manner (0.01–1 mM). The same concentrations of PCMBS did not affect the Ca2+-independent K+ current (IKv), but caused a transient enhancement of Ca2+ current (Ica). The inhibition of IKcaby PCMBS is similar to the previously reported effects of hypoxia, and suggests a central role for the channels underlying this current in chemotransduction.