Abstract
Contraction of taenia coli induced by KCl (10-40 mM), angiotensin (5 x 10-7 M) or acetylcholine (10-5 M) was partially inhibited by chlorpromazine (10-5 M), Dibenamine (10-4 M) and phenoxybenzamine (10-4 M). Dihydroergotamine (10-4 M), phentolamine (10-4 M) and pronethanol (10-4 M) had no effect. Contraction induced by BaCl2 (10 mM) was unaffected by chlorpromazine, Dibenamine or potassium. The inhibitory action of the blockers of potassium-induced contraction was prevented by a high external Ca++. Increased Ca45 uptake during contractions produced by potassium or acetylcholine was inhibited by chlorpromazine, Dibenamine and potassium. All three also decreased the Ca45 uptake of unstimulated taenia coli. These results suggest that the inhibitory action of these three agents on potassium-induced contraction is mediated by an inhibition of calcium movement.
Footnotes
- Received May 4, 1967.
- Accepted November 17, 1967.
- © 1968 by The Williams & Wilkins Company
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