Inhibitory Effects of Potassium Channel Blockers on Carbachol-induced Contraction in Rat Detrusor Muscle
Journal of Korean Medical Science
; : 701-706, 2003.
Article
in En
| WPRIM
| ID: wpr-221852
Responsible library:
WPRO
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.
Key words
Full text:
1
Index:
WPRIM
Main subject:
Protein Binding
/
Vasodilator Agents
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Urinary Bladder
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Carbachol
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Calcium Channel Blockers
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Nicardipine
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4-Aminopyridine
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Calcium
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Rats, Sprague-Dawley
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Tetraethylammonium
Limits:
Animals
Language:
En
Journal:
Journal of Korean Medical Science
Year:
2003
Type:
Article