Abstract
1. The effects of the putative alpha 1B-adrenoceptor antagonist, chloroethylchlonidine (CEC), on tension responses of the rat isolated whole vas deferens to single and multiple pulses of electrical field stimulation have been evaluated by use of a microcomputer system which enables the averaging of like-responses throughout their time course. 2. CEC (10(-7) to 3 x 10(-6) M) selectively and in a concentration-dependent manner blocked the noradrenergic component of the response to a single field stimulus in the absence or presence of nifedipine (10(-5) M, which blocked the purinergic but not the noradrenergic component of the response). The concentration-response curve of the vas to exogenously-applied noradrenaline (NA) was unaffected by CEC (10(-6) M) but was flattened by nifedipine (10(-5) M). 3. The tension response to 10 Hz trains of pulses was biphasic, with an early (less than 2 s) and a plateau (greater than 4 s) phase. We deduce from our pharmacological analysis that the early phase contains a putative alpha 1B-adrenoceptor component (susceptible to CEC or prazosin but not to nifedipine) and a P2-purinoceptor component (susceptible to suramin or nifedipine) whereas the plateau phase contains an alpha 1A-adrenoceptor component (susceptible to prazosin or nifedipine but not to CEC) and a P2-purinoceptor component (susceptible to suramin or nifedipine). 4. We suggest that the putative alpha 1B-adrenoceptors may be functionally confined to the synaptic region whereas the putative alpha 1A-adrenoceptors are excluded from this region.(ABSTRACT TRUNCATED AT 250 WORDS)
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Selected References
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- Anton P. G., Duncan M. E., McGrath J. C. An analysis of the anatomical basis for the mechanical response to motor nerve stimulation of the rat vas deferens. J Physiol. 1977 Dec;273(1):23–43. doi: 10.1113/jphysiol.1977.sp012079. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Berridge M. J. Inositol trisphosphate-induced membrane potential oscillations in Xenopus oocytes. J Physiol. 1988 Sep;403:589–599. doi: 10.1113/jphysiol.1988.sp017266. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Brown C. M., McGrath J. C., Summers R. J. The effects of alpha-adrenoceptor agonists and antagonists on responses of transmurally stimulated prostatic and epididymal portions of the isolated vas deferens of the rat. Br J Pharmacol. 1979 Aug;66(4):553–564. doi: 10.1111/j.1476-5381.1979.tb13694.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Brown D. A., Docherty J. R., French A. M., MacDonald A., McGrath J. C., Scott N. C. Separation of adrenergic and non-adrenergic contractions to field stimulation in the rat vas deferens. Br J Pharmacol. 1983 Jun;79(2):379–393. doi: 10.1111/j.1476-5381.1983.tb11010.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Dunn P. M., Blakeley A. G. Suramin: a reversible P2-purinoceptor antagonist in the mouse vas deferens. Br J Pharmacol. 1988 Feb;93(2):243–245. doi: 10.1111/j.1476-5381.1988.tb11427.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- French A. M., Scott N. C. A comparison of the effects of nifedipine and verapamil on rat vas deferens. Br J Pharmacol. 1981 Jun;73(2):321–323. doi: 10.1111/j.1476-5381.1981.tb10424.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- French A. M., Scott N. C. Evidence to support the hypothesis that ATP is a co-transmitter in rat vas deferens. Experientia. 1983 Mar 15;39(3):264–266. doi: 10.1007/BF01955295. [DOI] [PubMed] [Google Scholar]
- Han C., Abel P. W., Minneman K. P. Alpha 1-adrenoceptor subtypes linked to different mechanisms for increasing intracellular Ca2+ in smooth muscle. Nature. 1987 Sep 24;329(6137):333–335. doi: 10.1038/329333a0. [DOI] [PubMed] [Google Scholar]
- Han C., Abel P. W., Minneman K. P. Heterogeneity of alpha 1-adrenergic receptors revealed by chlorethylclonidine. Mol Pharmacol. 1987 Oct;32(4):505–510. [PubMed] [Google Scholar]
- Hoyle C. H., Knight G. E., Burnstock G. Suramin antagonizes responses to P2-purinoceptor agonists and purinergic nerve stimulation in the guinea-pig urinary bladder and taenia coli. Br J Pharmacol. 1990 Mar;99(3):617–621. doi: 10.1111/j.1476-5381.1990.tb12979.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Leclerc G., Rouot B., Schwartz J., Velly J., Wermuth C. G. Studies on some para-substituted clonidine derivatives that exhibit an alpha-adrenoceptor stimulant activity. Br J Pharmacol. 1980;71(1):5–9. doi: 10.1111/j.1476-5381.1980.tb10902.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Leff P., Wood B. E., O'Connor S. E. Suramin is a slowly-equilibrating but competitive antagonist at P2x-receptors in the rabbit isolated ear artery. Br J Pharmacol. 1990 Nov;101(3):645–649. doi: 10.1111/j.1476-5381.1990.tb14134.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- McGrath J. C. Alpha-adrenoceptor antagonism by apoyohimbine and some observations on the pharmacology of alpha-adrenoceptors in the rat anococcygeus and vas deferens. Br J Pharmacol. 1984 Aug;82(4):769–781. doi: 10.1111/j.1476-5381.1984.tb16473.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- McGrath J. C. Evidence for more than one type of post-junctional alpha-adrenoceptor. Biochem Pharmacol. 1982 Feb 15;31(4):467–484. doi: 10.1016/0006-2952(82)90147-2. [DOI] [PubMed] [Google Scholar]
- Minneman K. P., Han C., Abel P. W. Comparison of alpha 1-adrenergic receptor subtypes distinguished by chlorethylclonidine and WB 4101. Mol Pharmacol. 1988 May;33(5):509–514. [PubMed] [Google Scholar]
- Morrow A. L., Creese I. Characterization of alpha 1-adrenergic receptor subtypes in rat brain: a reevaluation of [3H]WB4104 and [3H]prazosin binding. Mol Pharmacol. 1986 Apr;29(4):321–330. [PubMed] [Google Scholar]
- Sneddon P., Westfall D. P. Pharmacological evidence that adenosine triphosphate and noradrenaline are co-transmitters in the guinea-pig vas deferens. J Physiol. 1984 Feb;347:561–580. doi: 10.1113/jphysiol.1984.sp015083. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Wilson V. G., Brown C. M., McGrath J. C. Are there more than two types of alpha-adrenoceptors involved in physiological responses? Exp Physiol. 1991 May;76(3):317–346. doi: 10.1113/expphysiol.1991.sp003501. [DOI] [PubMed] [Google Scholar]
