Erowid References Database
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McGrath JC.
“Adrenergic and 'Non-Adrenergic' Components in the Contractile Response of the Vas Deferens to a Single Indirect Stimulus”.
J.Physiol.. 1978;283:23-29.
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Abstract
The contractile response of the vas deferens to a single indirect stimulus was studied. - Vasa deferentia were isolated from male Wistar rats (250 -300 g), guinea pigs (500-600 g) and mice (Parkes strain, 40-50 g). The effects of single field electric shock stimulation are described. The effects of phentolamine (CIBA-Geigy, 10-7-10-5 M), prazosin (Pfizer, 5 x 10 -8-5 x 10-7 M), azapetine (Roche, 10-8 - 10-7 M) and yohimbine (Sigma-Chem., 5 x 10-7 - 10-5 M) on stimulation were studied. The 1 st phase of the response was unaffected but there was a dose-related inhibition of the 2nd phase of the epididymal response. Concentrations of each agent which produced maximal inhibition of the 2nd phase could also potentiate the let phase. Azapetine was most effective in this respect and at concentrations of 6 x 10-6 M and above could also produce rhythmic contractions. of the tissue which could not be abolished by other a-adrenoceptor blockers. A dose-related inhibition of the 1st phase was produced by 10 /to 10 4M apomorphine (Macfarlan); the 2nd phase of the response was increased in height and duration by 10 5-10 4M apomorphine. 10 4M Apomorphine also produced rhythmic contraction of the epididymal but not of the prostatic portion. LSD (Sandoz, 10-7 M) inhibited the 2nd phase but not the 1st phase of the response. Guanethidine (CIBA-Geigy, 10-7 - 10-5 M) produced a dose-related inhibition of the 1st phase of the response. 10-5 M And above also produced rhythmic contraction of the tissue and could potentiate nerve reaponses. The sympathomimetic action was prevented by the addition of prazosin (5 x 10 7M). Cocaine (CIBA-Geigy. 10-6M) increased the height and duration of the 2nd -phase of response to a sinle pulse and it became rhythmic in nature. When cocaine (10-6M) and phentolamine (10-6M) were given together a monophasic response similar in height to the initial 1st phase was seen. Cocaine (6 x 10-6M) produced rhythmic contractions. Reserpine (Koch-Light, 3 mg/kg, i.p.) removed the 2nd component of the response to a single stimulus leaving in the epididymal portion, a monophasic response with an early peak. The response in the prostatic portion was not reduced following reserpine. In the mouse vas deferens 2 distinct phases were found. Cocaine (10-6M) selectively potentiated the 2nd phase, but 10-5 M cocaine reduced the size of the potentiation. Phentolamine (10-6M) removed the 2nd phase leaving the 1st phase intact. In the guinea pig there was less distinction between the 2 phases. In the presence of cocaine (10-6M) the 2nd phase was potentiated and after phentolamine (10-6-10-5 M) was inhibited. Neither drug affected the 1st phase.
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