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Low dihydropyridine receptor density in vasa deferentia of castrated rats
Author(s) -
Castillo C.J.F.,
Lafayette S.,
CaricatiNeto A.,
Sette M.,
Jurkiewicz N.H.,
García A.G.,
Jurkiewicz> A.
Publication year - 1992
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1992.tb14241.x
Subject(s) - vas deferens , endocrinology , medicine , dihydropyridine , receptor , chemistry , calcium
Radioligand binding studies in crude membrane preparations of vasa deferentia of normal rats, with the 1,4‐dihydropyridine (+)‐[ 3 H]‐PN200–110 (isradipine) showed typical saturation isotherms. The binding exhibited a K D of 259 ± 60 p m and B max of 144 ± 20 fmol mg −1 protein. The low K D and the stereoselective displacement of (+)‐[ 3 H]‐PN200–110 binding by (+)‐ and (−)‐PN200–110 and by nifedipine suggests that these tissues contain dihydropyridine receptors probably coupled to voltage‐sensitive, L‐type calcium channels. In membrane preparations from vasa deferentia from rats castrated 30 days previously the maximum specific binding was 25 ± 10 fmol mg −1 protein, representing only 11% of total binding; thus, the calculation of reliable K D values was not feasible. These findings suggest that a testicular hormone, possibly testosterone, plays an important role in the regulation of dihydropyridine‐sensitive, voltage‐dependent calcium channels in the rat vas deferens.