Identification of putative calcium channels in skeletal muscle microsomes |
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Authors: | D R Ferry H Glossmann |
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Institution: | Rudolf Buchheim-Institut für Pharmakologie, Justus-Liebig-Universität, Frankfurter Straße 107, D-63 Gießen, FRG |
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Abstract: | Saturable binding sites for the labelled calcium antagonist (+/-)3H]nimodipine were found in guinea-pig hind limb skeletal muscle homogenates. Binding sites were enriched in a microsomal pellet by differential centrifugation of the homogenate. 3H]Nimodipine binding (Kd = 1.5 +/- 0.03 nM, Bmax = 2.1 +/- 0.25 pmol/protein, at 37 degrees C) copurified (6-fold) in this fraction with 3H]ouabain binding (6.6-fold) and 125I-alpha-bungarotoxin binding (5-fold). d-cis-Diltiazem (but not 1-cis-diltiazem) stimulated (+/-) 3H]nimodipine binding (ED50 1 microM) by increasing the Bmax. Binding sites discriminated between the optical enantiomers of 1.4-dihydropyridine calcium antagonists and the optically pure enantiomers of D-600. The data confirm, with biochemical techniques, the presence of 1,4-dihydropyridine and (+/-) D-600 inhibitable calcium channels in skeletal muscle, previously found with electrophysiological techniques. |
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Keywords: | Skeletal muscle Calcium channel Antagonist Receptor Allosterism Nimodipine |
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