Calcium-dependent after-hyperpolarization in dissociated bullfrog sympathetic neurons.
Whole-cell recordings were made from dissociated bullfrog sympathetic neurons. Tetraethylammonium (30 mM) and apamin (100 nM) were added to the superfusate to eliminate the known calcium-activated potassium currents termed Ic and IAHP. Under these conditions, the action potential carried by calcium ions was followed by a prolonged (10-60 s) after-hyperpolarization. A current component (IAC) underlying the after-hyperpolarization was eliminated by barium (2 mM) and showed voltage-dependence identical to that of a M-type potassium current. I concluded that the after-hyperpolarization is caused not only by IAHP but also by the calcium-dependent potentiation of M-current.
Tokimasa
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Department of Physiology, Tokai University Medical School, Bohseidai, Isehara, Japan. tokimasa@is.icc.u-tokai.ac.jp
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D008564:Membrane Potentials / Q000502:physiology*; D018408:Patch-Clamp Techniques; D011892:Rana catesbeiana; D013564:Sympathetic Nervous System / Q000502:physiology*
D002118:Calcium