(—)‐[3H]Desmethoxyverapamil, a novel Ca2+ channel probe

FEBS Letters

Goll, A.¹  Glossmann, H.¹  Schober, M.¹  Striessnig, J.¹  Ferry, D.R.¹ 

[1] Rudolf-Buchheim-Institut für Pharmakologie, Justus-Liebig Universität, Frankfurter Strosse 107, D-6300 Giessen, FRG

关键词: (—)-[3H]Deslnethoxyverapamil;    Skeletal muscle;    Ca2+-channel;    Target size;   

DOI  :  10.1016/0014-5793(84)81199-0

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

(—)-[³H]Desmethoxyverapamil (2,7-dimethyl-3-(3,4-dimethoxyphenyl)-3-cyan-7-aza-9-(3-methoxyphenyl)-nonanhydrochloride) was used to label putative Ca²⁺ channels in guinea pig skeletal muscle. The binding sites for (—)-[³H]desmethoxyverapamil co-purified with t-tubule membrane markers in an established subcellular fractionation procedure. (—)-[³H]Desmethoxyverapamil bound to partially purified t-tubule membranes with a K _D of 2.2 ± 0.1 nM and a B _maxof 18 ± 4 membrane protein at 25°C. Binding was stereoselectively inhibited by phenylalkylamine Ca²⁺ antagonists and in a mixed, non-competitive fashion by the benzoihiazepine Ca²⁺ antagonist d-cis-diltiazem and the 1,4-dihydropyridine Ca²⁺ antagonist (+)-PN 200-110. Target size analysis of the (—)-[³H]desmethoxyverapamil drug receptor site revealed a molecular mass of 107 ± 2 kDa. In contrast, the target size of the allosterically coupled benzothiazepine drug receptor site, labelled by d-cis-[³H]diltiazem, was 130.5 ± 4 kDa (p <0.01) and of the 1,4-dihydropyridine binding site 179 kDa, when labelled with [³H]nimodipine. It is concluded that (—)-[³H]desmethoxyverapamil is an extremely useful radioligand for the phenylalkylamine-selective receptor site of the t-tubule localized Ca²⁺ channel which is allosterically linked to two other distinct drug receptor sites.

【 授权许可】

Unknown