Abstract
The recently described calcium channel agonists Bay-K8644 and CGP-28392 have been used to induce long-term opening of calcium channels from purified rat muscle transverse tubules (t-tubules) incorporated into planar phospholipid bilayers. Agonist-open channels are selective for divalent cations (except Mg++), display voltage-dependent kinetics, and are blocked by the calcium channel antagonist, nitrendipine. The sensitivity to dihydropyridine agonists and antagonists indicate that a pool of t-tubule calcium channels remain functional after membrane fractionation and purification.