ABSTRACT
Ryanodine receptor Ca2+ channels have been identified in skeletal, cardiac, and smooth muscles and in nonmuscle cells of essentially all animals, that were tested (Meissner 1994a, b; Sutko and Airey, 1996). Together with the inositol 1, 4, 5,-trisphosphate sensitive Ca2+ channels (Vergara et al., 1985; Volpe et al., 1985; Hidalgo and Jaimovich, 1989; Hannon et al., 1992; Gorza et al., 1993; Kijima et al., 1993; Moschella and Marks, 1993; Moschella et al., 1995) they play a major role in intracellular signaling and Ca2+ homeostasis (Clapham, 1995; Michikawa et al., 1996; Dulhunty et al., 1996; Berridge, 1997; Putney, 1997; Franzini-Armstrong and Protasi, 1997; Sitsapesan and Williams, 1997).
