Abstract
Single-channel currents were recorded from two classes of Ca2+ channels in visceral smooth muscle cells isolated from the stomach of the toad, Bufo marinus: a class of small-conductance channels (approximately 11 pS) and a class of large-conductance channels (approximately 26 pS). Small-conductance channels were present in a majority of patches and gave rise to a slowly inactivating current (t1/2 ≈ 250 ms at 0 mV). Openings of large-conductance channels could be unequivocally resolved only in the presence of the dihydropyridine Ca2+ agonist Bay K 8644. Two subtypes of the large-conductance channels were found — those with a very slow rate of decay (> 500 ms) and those with a faster one (< 100ms). Large-conductance channels resemble L-type Ca2+ channels of other preparations. Small-conductance channels do not fit unambiguously into the other existing categories (i.e., N or T). Correspondence between single-channel and macroscopic Ca2+ currents is discussed.
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Vivaudou, M.B., Singer, J.J. & Walsh, J.V. Multiple types of Ca2+ channels in visceral smooth muscle cells. Pflügers Archiv 418, 144–152 (1991). https://doi.org/10.1007/BF00370463
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DOI: https://doi.org/10.1007/BF00370463