Oscillation of [Ca2+]i-linked K+ conductance in bullfrog sympathetic ganglion cell is sensitive to intracellular anions

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Abstract
The intracellular free Ca2+ ([Ca2+]i) regulates the K+ conductance (GK) of the many types of cell membrane. The Ca2+ influx during an action potential activates this [Ca2+]i-linked GK in most neurones. In caffeine-treated sympathetic ganglion cells, however, Ca2+ released from an intracellular Ca2+ reservoir site analogous to the sarcoplasmic reticulum (SR) of the muscle (see ref. 12) causes activation of the GK, which results in slow oscillatory hyperpolarisations (caffeine hyperpolarisation, C-hyperpolarisation). Such a release of Ca2+ linked to the GK of the membrane seems important for understanding the role of the intracellular organelles in the control of membrane activities of a neurone. We report here the mechanism of the slow oscillatory hyperpolarisations recorded from the bullfrog sympathetic ganglion cell in Ringer solution. It is found that these hyperpolarisations are generated by a [Ca2+]i-linked GK system and are highly sensitive to anions in an intracellular recording electrode, probably to intracellular anions.