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KMID : 0376219780150010057
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Chonnam Medical Journal
1978 Volume.15 No. 1 p.57 ~ p.69
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Inhibitory and potentiating effect of McN-A-343 on the contractile response of the guinea-pig vas deferens to electrical stimulation
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Abstract
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1. The pharmacological actions of McN-A-343 were investigated in the guinea-pig vas deferens preparations.
2. Small doses of McN-A-343(3x10-9_10-7 M) inhibited the twitch response of the guinea-pig vas deferens to field stimulation (2-4OHz) and larger doses of McNA-343(10-54x1O-5M) potentiated it.
3. Atropine and thymoxamine made the inhibition of the twitch response of the guinea-pig vas deferens by McN-A-343 to field stimulation more marked, and phentolamine and yohimbine abolished the inhibitory response. Clonidine also produced the inhibition of the twitch response. McN-A-343 did not cause further inhibition of the twitch response, when the response was slready inhibited by clonidine.
4. The potentiation of the twitch response of the guinea-pig vas deferens by McN-A-343 to field stimulation was markedly depressed in the presence of atropine, bretylium and thymoxamine, and the potentiation was not affected by chlorisondamine, cocaine, phentolamine and reserpine-pretreatment.
5. The twitch response of the guinea-pig vas deferens to field stimulation was potentiated by muscarine, methacholine and acetylcholine. The potentiation by muscarine was not observed in the presence of atropine and thymoxamine.
6. The contractile response to norepinephrine(NE) and phenylephrine was potentiated in the presence of McN-A-343(2 x 10-5M) but the response to acetylcholine was not affected. When the contractile response to NE was already. potentiated by McN-A-343 or cocaine, cocaine or McN-A-343 did not produce further potentiation respectively.
7. McN-A-343 caused the guinea-pig vas deferens to contract in the presence of tyramine, ´but cocaind,".did not. Tyrarnine itself-did not produce contraction.
8. The above results; seem, to indicate that McN-A-343 has following actions in the guinea-pig vas deferens:1) the inhibitory effect on NE-release-by acting´ as an agonise on the presynaptic a adrenoceptors,2) the facilitating effect on: NE-release, by acting as an agonist on the muscarinic receptors of the adrenergic nerve endings,3) the inhibitory effect on NE-uptake.
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