Multiple types of Ca2+channels in visceral smooth muscle cells

✍ Scribed by Michel B. Vivaudou; Joshua J. Singer; John V. Walsh

• Publisher: Springer
• Year: 1991
• Tongue: English
• Weight: 961 KB
• Volume: 418
• Category: Article
• ISSN: 0031-6768
• DOI: 10.1007/bf00370463

✦ Synopsis

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 approximately 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 (greater than 500 ms) and those with a faster one (less than 100 ms). 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.