Effects of calcium and verapamil on vesicourethral smooth muscle of rabbits

Urology
O P KhannaR F McMichael

Abstract

Isolated smooth muscle strips from the rabbit bladder body, bladder base, and proximal urethra were contracted with ionic calcium (Ca2+) alone and with the calcium-selective ionophore A23187, acetylcholine, norepinephrine, adenosine triphosphate (ATP), and direct electrical stimulation. The effects of Ca2+ and the calcium entry blocker verapamil on spontaneous muscle activity and on contractions induced by these agonists were examined. Ca2+ -free Tyrode's solution and verapamil, 1 x 10(-7)M and above, relaxed all of the vesicourethral smooth muscle strips. In addition verapamil, 1 x 10(-8) to 1 x 10(-6) M depending on the particular stimulant employed, noncompetitively inhibited smooth muscle contractions elicited by Ca2+, acetylcholine, norepinephrine, ATP, and direct electrical stimulation. It was concluded that transmembrane Ca2+ influx was important not only in the maintenance of tone and spontaneous phasic muscle activity, but also for the activation of contractions induced by all of the stimulants tested. The data also suggest that intracellular Ca2+ fraction(s) participate in the contractile responses to acetylcholine and norepinephrine challenge, but not to contractions evoked by ATP or electricity.

References

Jan 1, 1977·Annual Review of Pharmacology and Toxicology·A Fleckenstein
Oct 1, 1977·Urology·O P KhannaR F McMichael
Dec 17, 1976·Deutsche medizinische Wochenschrift·J BödekerR Nagel
Jan 1, 1976·The Japanese Journal of Physiology·S Sunano
Jan 1, 1972·Pflügers Archiv : European journal of physiology·K Golenhofen, E Lammel
Jul 1, 1972·British Journal of Pharmacology·A Eckenfels, J R Vane
Jan 1, 1980·Annual Review of Pharmacology and Toxicology·W A Catterall

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Citations

Dec 13, 2002·Neurourology and Urodynamics·Robert J Theobald
Jul 1, 1997·International Journal of Urology : Official Journal of the Japanese Urological Association·Y SasakiK Kimura
Feb 1, 1989·The Journal of Urology·J G SussetP Biancani
Sep 1, 1987·The Journal of Urology·S B MalkowiczR M Levin
Dec 1, 1984·British Journal of Pharmacology·N SatakeS Ueda
Jan 1, 1986·Acta Pharmacologica Et Toxicologica·K E Andersson, A Forman

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