Title

On the characterization of dopamine-induced contractile response of rat anococcygeus muscle preparation

Document Type

Article

Publication Date

1994

Abstract

Presence of specific dopamine (DA) receptors and their characterization was attempted in rat anococcygeus muscle preparation. Dopamine (10 -6 M) and B-HT 920 (10 -6 M) produced concentration dependent contractions of the rat anococcygeus muscle preparation. The response of DA was shifted towards right in presence of haloperidol (10 -6 M; pA 2 = 6.8) and sulpiride (10 -4 M) in a competitive manner. α 2 antagonists yohimbine (10 -5 M) and idazoxan (10 -5 M) blocked the response to DA in a competitive manner, while α 1 antagonist prazosin (10 -5 M) completely blocked the response to DA. SCH 23390 (10 -5 M), a D 1 DA antagonist potentiated the response to DA. Reserpinization (5 mg/kg, 24 hr prior) brought about a shift towards the right, and this response was similarly blocked by haloperidol, sulpiride and yohimbine without affecting the maximum response. Desipramine (10 -5 M) blocked the response of DA in a non-competitive manner. Pretreatment of animals with desipramine (10 mg/kg) followed by reserpine, brought about a reversal of action of reserpine. The response to B-HT 920 (10 -6 M), was blocked similarly by haloperidol and yohimbine. However, the effect of desipramine was more pronounced when compared to DA per se. SKF 38393, a D 1 DA agonist, potentiated the response to B-HT 920. The findings suggest the presence of both D 1 and D 2 DA receptors in rat anococcygeus muscle and that DA also acts on adrenergic receptors to produce a contractile response of this muscle preparation.

Publication Title

Indian journal of experimental biology

Volume

32

Issue

3

First Page

176

Last Page

179

Comments

This article was published in Indian journal of experimental biology, Volume 32, Issue 3, Pages 176-179.

The published version is not available online.

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