Skip to main content
British Journal of Pharmacology logoLink to British Journal of Pharmacology
. 1989 Apr;96(4):837–842. doi: 10.1111/j.1476-5381.1989.tb11892.x

Differential susceptibility of cholinergic and noncholinergic neurogenic responses to calcium channel blockers and low Ca2+ medium in rat urinary bladder.

M B Bhat 1, S K Mishra 1, V Raviprakash 1
PMCID: PMC1854416  PMID: 2743079

Abstract

1. The influence of calcium channel blockers and low Ca2+ medium on the neurogenic responses to single pulse electric field stimulation in rat urinary bladder has been examined. 2. Single pulse stimulation evoked a biphasic contractile response consisting of a fast component with a time to peak of 0.72 +/- 0.05 s and a slow component that reached a maximal tension at 2.8 +/- 0.21 s, possibly mediated by two different neurotransmitters. 3. Atropine (3 x 10(-6) M) selectively inhibited the slow component without altering the fast component, suggesting the involvement of cholinergic and non-cholinergic neurotransmitters, respectively. 4. Reducing Ca2+ in the medium to 1/4 of the normal, abolished the slow component of the neurogenic response while the fast contractile response was not altered which may indicate a relatively greater dependence of the cholinergic component on extracellular Ca2+ than the noncholinergic one. 5. The IC50 values for the fast component with respect to verapamil and diltiazem were 1.08 microM and 1.76 microM, respectively. The greater susceptibility of the slow component to calcium channel blockers (IC50 values of verapamil: 0.07 microM and of diltiazem: 0.25 microM) indicates the differential activation of slow calcium channels by the endogenously released substances. 6. Calcium channel blockers inhibited the ATP-induced contraction which was comparable to that of the non-cholinergic component of the neurogenic response suggesting the involvement of ATP as a possible neurotransmitter. 7. Ach-induced contractions were relatively less susceptible to calcium channel blockers and low Ca2+ medium than was the atropine-sensitive cholinergic component of the neurogenic response.

Full text

PDF
840

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Batra S., Sjögren C., Andersson K. E., Fovaeus M. Source of calcium for contractions induced by depolarization and muscarinic receptor stimulation in rabbit urinary bladder. Acta Physiol Scand. 1987 Aug;130(4):545–551. doi: 10.1111/j.1748-1716.1987.tb08175.x. [DOI] [PubMed] [Google Scholar]
  2. Brown C., Burnstock G., Cocks T. Effects of adenosine 5'-triphosphate (ATP) and beta-gamma-methylene ATP on the rat urinary bladder. Br J Pharmacol. 1979 Jan;65(1):97–102. doi: 10.1111/j.1476-5381.1979.tb17337.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. 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]
  4. Fujii K. Evidence for adenosine triphosphate as an excitatory transmitter in guinea-pig, rabbit and pig urinary bladder. J Physiol. 1988 Oct;404:39–52. doi: 10.1113/jphysiol.1988.sp017277. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Godfraind T., Miller R., Wibo M. Calcium antagonism and calcium entry blockade. Pharmacol Rev. 1986 Dec;38(4):321–416. [PubMed] [Google Scholar]
  6. Hoyle C. H., Burnstock G. Atropine-resistant excitatory junction potentials in rabbit bladder are blocked by alpha,beta-methylene ATP. Eur J Pharmacol. 1985 Aug 15;114(2):239–240. doi: 10.1016/0014-2999(85)90635-1. [DOI] [PubMed] [Google Scholar]
  7. Huddart H., Butler D. J. Field stimulation responses of rat urinary bladder detrusor smooth-muscle. Dependence upon slow calcium channel activity determined by K+ depolarization and calcium antagonists. Gen Pharmacol. 1986;17(6):695–703. doi: 10.1016/0306-3623(86)90302-2. [DOI] [PubMed] [Google Scholar]
  8. Kasakov L., Burnstock G. The use of the slowly degradable analog, alpha, beta-methylene ATP, to produce desensitisation of the P2-purinoceptor: effect on non-adrenergic, non-cholinergic responses of the guinea-pig urinary bladder. Eur J Pharmacol. 1982 Dec 24;86(2):291–294. doi: 10.1016/0014-2999(82)90330-2. [DOI] [PubMed] [Google Scholar]
  9. Maggi C. A., Santicioli P., Meli A. Pharmacological evidence for the existence of two components in the twitch response to field stimulation of detrusor strips from the rat urinary bladder. J Auton Pharmacol. 1985 Sep;5(3):221–229. doi: 10.1111/j.1474-8673.1985.tb00123.x. [DOI] [PubMed] [Google Scholar]
  10. Raviprakash V., Mishra S. K., Panda J. N. Effect of verapamil on the non-adrenergic response of the field stimulated rat vas deferens. Naunyn Schmiedebergs Arch Pharmacol. 1985 Dec;331(4):347–350. doi: 10.1007/BF00500817. [DOI] [PubMed] [Google Scholar]
  11. Warter J. M., Imler M., Marescaux C., Chabrier G., Rumbach L., Micheletti G., Krieger J. Sodium valproate-induced hyperammonemia in the rat: role of the kidney. Eur J Pharmacol. 1983 Feb 18;87(2-3):177–182. doi: 10.1016/0014-2999(83)90327-8. [DOI] [PubMed] [Google Scholar]

Articles from British Journal of Pharmacology are provided here courtesy of The British Pharmacological Society

RESOURCES