INHIBITION BY THE PUTATIVE POTASSIUM CHANNEL OPENER PINACIDIL OF THE ELECTRICALLY-EVOKED RELEASE OF ENDOGENOUS DOPAMINE AND NORADRENALINE IN THE RAT VAS-DEFERENS

• Tipo: Artigo em Revista Científica Internacional
• Data: 1990

Autores

soares-da-silva, p (Autor) FMUP; Fernandes MH (Autor) FMDUP

Revista

Título: Naunyn-Schmiedeberg's Archives of Pharmacology

Vol. 342

Páginas: 415-421

ISSN: 0028-1298

Editora: Springer Nature

Indexação

ISI Web of Knowledge - 18 Citações

Scopus - 18 Citações

Outras Informações

ID Authenticus: P-001-RGM

Abstract (EN): The effect of pinacidil on the release of endogenous noradrenaline and dopamine from the sympathetic innervation of the rat vas deferens was examined. Amine release was evoked by electrical stimulation (1, 2, 5 and 10 Hz) or by depolarization with high potassium (75 mmol/l) in the medium. Dopamine and noradrenaline were measured by means of high pressure liquid chromatography with electrochemical detection. Pinacidil (1, 5, 10 and 50 ¿mol/l) produced a concentration-dependent inhibition of the electrically stimulated (2 Hz) overflow of noradrenaline and dopamine. Only pinacidil 50 ¿mol/l increased the spontaneous loss of dopamine and noradrenaline. The inhibitory effects of pinacidil (5 ¿mol/l) on amine overflow were also observed at other frequencies of stimulation (1, 5 and 10 Hz). The magnitude of the inhibitory effect or noradrenaline release was approximately the same at all frequencies (63% to 56% reduction); for dopamine, the higher the frequency of stimulation, the greater the inhibitory effect of pinacidil (up to 73% reduction). When the preparations were continuously stimulated for 70 min at 2 Hz, pinacidil (5 ¿mol/l) reduced the overflow of dopamine and noradrenaline during the first 40 or 30 min of stimulation only. The addition of phentolamine (1 ¿mol/l) to the perifusion medium slightly reduced the inhibitory effect of pinacidil on amino overflow, but the inhibition by pinacidil remained statistically significant. Tetraethylammonium (10 mmol/l) completely abolished the inhibitory effect of pinacidil (10 ¿mol/l). Pinacidil (5 ¿mol/l) did not reduce the potassium-evoked release of the amines. The results demonstrate that pinacidil impairs transmitter release from the sympathetic innervation of the rat vas deferens, probably as a consequence of the opening of potassium channels.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 7