LOW DIHYDROPYRIDINE RECEPTOR DENSITY IN VASA DEFERENTIA OF CASTRATED RATS

• Autor(a) principal: Castillo, CJF
• Data de Publicação: 1992
• Outros Autores: Lafayette, Simone Sette Lopes [UNIFESP], Caricati-Neto, Afonso [UNIFESP], Sette, Mario [UNIFESP], Jurkiewicz, Neide Hyppolito [UNIFESP], Garcia, Antonio G., Jurkiewicz, Aron [UNIFESP].
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNIFESP
• Texto Completo: http://onlinelibrary.wiley.com/doi/10.1111/j.1476-5381.1992.tb14241.x/full; http://repositorio.unifesp.br/handle/11600/43174
• topic: DIHYDROPYRIDINE RECEPTORS; VAS DEFERENS; CALCIUM CHANNELS; CASTRATION

Radioligand binding studies in crude membrane preparations of vasa deferentia of normal rats, with the 1,4-dihydropyridine (+)-[H-3]-PN200-110 (isradipine) showed typical saturation isotherms. The binding exhibited a K(D) of 259 +/- 60 pM and B(max) of 144 +/- 20 fmol mg-1 protein. The low K(D) and the stereoselective displacement of (+)-[H-3]-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.