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Query: UNIPROT:P56851 (epididymal)
 11,273 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study was undertaken in an attempt to explain why in some of the tissues in which noradrenaline and ATP act as co-transmitters the noradrenergic component predominates, while in others the predominant component is purinergic. Four different tissues were used: the epididymal portion of the rat vas deferens and the rabbit ear artery, tissues where the noradrenergic component predominates, and the prostatic portion of the rat vas deferens and the rabbit jejunal artery, where the purinergic component predominates. The noradrenaline content as well as the electrically-evoked release of noradrenaline were determined in all tissues. To determine the evoked release, the tissues were pretreated with pargyline (1 mmol.l-1) and then exposed to 3H-noradrenaline, washed out and transmurally stimulated (1 Hz). In addition, the influence of inhibition of neuronal uptake by desipramine (40 nmol.l-1) on pre- and postjunctional effects of adrenaline and alpha-methylnoradrenaline (and/or noradrenaline) was compared. The noradrenaline content of the tissues averaged: 17.4, 23.2, 3.1, and 4.8 micrograms.g-1 for the epididymal and the prostatic portions of the rat vas deferens and for the ear and the jejunal arteries of the rabbit, respectively. The fractional electrically-evoked release of 3H-noradrenaline was 2.02 and 2.04 x 10(-5) for the epididymal and the prostatic portions of the rat vas deferens, respectively, and 3.33 and 3.26 x 10(-5) for the ear and the jejunal arteries of the rabbit, respectively. Desipramine enhanced much more the postjunctional effect of noradrenaline, adrenaline, and alpha-methylnoradrenaline in the epididymal than in the prostatic portion of the rat vas deferens.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Influence of neuronal uptake on pre- and postjunctional effects of alpha-adrenoceptor agonists in tissues with noradrenaline--ATP cotransmission. 168 21

Desipramine at 10(-7) M inhibited the neuronal uptake of noradrenaline and at 10(-6) M was also a alpha 1-adrenoceptor blocker. Desipramine potentiated and inhibited the responses of the epididymal and other portions to field stimulation, respectively, probably because the increased concentration of noradrenaline in the synapse was stimulating postjunctional alpha 1- and prejunctional alpha 2-adrenoceptors, respectively. Qualitatively the effects of prazosin, phentolamine and yohimbine on responses to added noradrenaline and to field stimulation were consistent with their being alpha 1-selective, nonselective and alpha 2-selective adrenoceptor antagonists. Quantitatively the effects of phentolamine and/or yohimbine on fast and slow responses to field stimulation and the modification of these effects by desipramine were dependent on the portion of vas, the response, the frequency of stimulation and the concentration of desipramine used.
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PMID:Modification by desipramine of the effects of alpha-adrenoceptor antagonists on the contractile responses of the trisected rat vas deferens. 286 90

The effect of uptake inhibitors, cocaine and desipramine, on the contractile response of the rat isolated vas deferens to the enantiomers of noradrenaline and adrenaline and to the corresponding deoxy-derivatives, dopamine and epinephline, was investigated. Cocaine (10(-6)M) significantly potentiated all six agonists; the effect was most marked for the laevo-isomers (-)-noradrenaline and (-)-adrenaline. Desipramine (10(-7) M) also potentiated (-)-noradrenaline, (+)-noradrenaline, (-)-adrenaline, (+)-adrenaline and epinephline but, in contrast, antagonized dopamine. This selective antagonism of dopamine by desipramine was also observed for the separated epididymal and prostatic ends of the rat vas deferens.
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PMID:Stereoselectivity of catecholamines: differential effects of cocaine and desipramine on catecholamine-induced contractions of the rat isolated vas deferens. 613 76

1 5-Hydroxytryptamine (5-HT) (5.16-1291 microM) produced a phasic contraction followed later by rhythmic contractions in the rat vas deferens, primarily in the epididymal half. 5-HT (129 microM) produced no response in Ca2+-free solution. Nifedipine (0.29 microM) or verapamil (2.04 microM) inhibited the initial phasic response to 5-HT, but inhibition of the rhythmic contractions required concentrations 5 fold (nifedipine) or 30 fold (verapamil) higher. 2 Methysergide (2.13 microM) abolished the phasic and reduced the frequency of the rhythmic contractions. Phentolamine (2.65 microM) did not affect the phasic response but reduced the amplitude of the rhythmic contractions. The combination of phentolamine (2.65 microM) and methysergide (2.13 microM) completely abolished the response to 5-HT (129 microM). 3 Desipramine (1.32 microM) had no effect on the phasic response to 5-HT (129 microM), but the rhythmic contractions were reduced in amplitude with no effect on their frequency. 4 In vasa deferentia removed from reserpine-treated or from guanethidine-denervated rats, both phasic and rhythmic components of the 5-HT (129 microM) contraction were augmented due to supersensitivity. 5 It is concluded that the phasic component of the 5-HT contraction is mediated by post-junctional 5-HT receptors, while the rhythmic component is mediated by the combination of post-junctional 5-HT receptors and noradrenaline released from neuronal stores. Assuming that nifedipine and verapamil are acting solely by inhibition of calcium channels, the phasic and rhythmic components of the 5-HT response may be mediated through separate Ca2+ channels. If this is correct, one channel might be a voltage-dependent channel and the other could be similar to, but distinct from the channel mediating the response to methoxamine.
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PMID:The contractile effects of 5-hydroxytryptamine on the rat isolated vas deferens. 715 Aug 68

1. The adaptational changes induced after chronic inhibition of neuronal noradrenaline uptake on both functional responsiveness of alpha 1-adrenoceptor activation and [3H]-prazosin binding were investigated in prostatic and epididymal portions of the rat vas deferens. 2. Contractile concentration-response curves to phenylephrine and saturation isotherms of [3H]-prazosin binding to homogenates of each of the portions of the bisected rat vas deferens were determined 48 h after the last injection of desipramine, nomifensine or nisoxetine (10 mg kg-1; i.p. for 14 days). 3. Treatment with both nomifensine and nisoxetine decreased the potency (pD2) of phenylephrine by about 10 and 8 fold respectively in the epididymal portion. However, administration of desipramine only reduced the potency of the alpha 1-adrenoceptor agonist by about 1.8 fold. None of the treatments modified the maximal effect (Emax) elicited by phenylephrine in this portion of the vas deferens. In the prostatic portion only the treatment with nomifensine (1.4 fold) and nisoxetine (1.8 fold) decreased the potency of phenylephrine; the maximal contraction elicited by the agonist after the treatments was also reduced. 4. Chronic treatment with either nomifensine or nisoxetine did not change the KD for [3H]-prazosin binding in either epididymal or prostatic membranes. However, these two treatments resulted in a significant decrease in the [3H]-prazosin Bmax in membranes in both portions of rat vas deferens. The reduction in density of alpha 1-adrenoceptors was higher in the epididymal than the prostatic half. Desipramine reduced the Bmax only in the epididymal portion. 5. These results indicate that differential regulation of ax-adrenoceptors in either portion of the rat vas deferens could result from a greater degree of activation of these receptors in the epididymal half after chronic inhibition of neuronal noradrenaline uptake. The different functional consequences of the loss of alpha l-adrenoceptors in each portion seems to be explained on the basis of a different relationship between the occupancy of the receptor and the response elicited.
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PMID:Modulation of alpha 1-adrenoceptors and functional consequences in the bisected rat vas deferens following chronic inhibition of neuronal noradrenaline uptake. 809 83