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Ca 2+ channel agonist BAY‐k 8644 does not elicit Ca 2+ release from skeletal muscle sarcoplasmic reticulum
Author(s) -
Zorzato Francesco,
Volpe Pompeo,
Salviati Giovanni,
Margreth Alfredo
Publication year - 1985
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(85)80719-5
Subject(s) - endoplasmic reticulum , nifedipine , biophysics , chemistry , calcium , skeletal muscle , agonist , voltage dependent calcium channel , membrane channel , ion transporter , membrane , biochemistry , endocrinology , receptor , biology , organic chemistry
BAY‐k 8644, a nifedipine analogue, promotes Ca 2+ influx into excitable cells via plasma membrane voltage‐sensitive Ca 2+ channels. We report here that sarcoplasmic reticulum (SR) Ca 2+ release channels are insensitive to BAY‐k 8644, as studied in highly purified isolated fractions and in chemically skinned fibers of rabbit skeletal muscle. This result suggests that a subcellular heterogeneity exists among Ca 2+ channels, at least with respect to drug‐receptor sites. In the course of this study, however we found that BAY‐k 8644 reversibly inhibits the SR Ca 2+ pump, i.e., it decreases Ca 2+ influx into the SR lumen, although at concentrations (IC 50 = 3‐5 × 10 −5 M) much higher than those effective on voltage‐sensitive Ca 2+ channels.