Inhibitory Effects of Potassium Channel Blockers on Carbachol-induced Contraction in Rat Detrusor Muscle
Journal of Korean Medical Science
;
: 701-706, 2003.
Artigo
em Inglês
| WPRIM
| ID: wpr-221852
ABSTRACT
We present accidental findings that potassium channel blockers, such as tetraethyl-ammonium (TEA) or 4-aminopyridine (4-AP), inhibit the sustained tonic contraction induced by carbachol in rat detrusor muscle strips. The relatively lower concentrations (5 mM) potentiated phasic contractions. The potentiation of phasic contraction was not observed in nicardipine pretreated condition. In nicardipine pretreated condition, the concentration-response curves for the negative inotropic effect of potassium channel blockers were shifted to the right by the increasing concentration of carbachol from 0.5 micrometer to 5 micrometer. IC50 was changed significantly from 0.19 to 0.64 mM (TEA) and from 0.21 to 0.96 (4-AP). Such inhibitory effects were also observed in Ca2+ depleted condition, where 0.1 mM EGTA and 1 micrometer thapsigargin were added into Ca2+ free solution. In conclusion, inhibitory effects of potasssium channel blockers on carbachol-induced contraction may be ascribed to the direct inhibition of receptor-agonist binding.
Texto completo:
DisponíveL
Índice:
WPRIM (Pacífico Ocidental)
Assunto principal:
Ligação Proteica
/
Vasodilatadores
/
Bexiga Urinária
/
Carbacol
/
Bloqueadores dos Canais de Cálcio
/
Nicardipino
/
4-Aminopiridina
/
Cálcio
/
Ratos Sprague-Dawley
/
Tetraetilamônio
Limite:
Animais
Idioma:
Inglês
Revista:
Journal of Korean Medical Science
Ano de publicação:
2003
Tipo de documento:
Artigo
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