Comparative Responses of Various Pharmacologic Agents on Contractility of the Smooth Muscle Strips of Rabbit Bladder

Jeong, Ho Hyeon; Lee, Jung Gu; Cho, Jae Heung

Abstract

Pharmacologic treatment of the detrusor hypocontractility(hyporeflexia) remains controversial issues. Clean intermittent self catheterization(CIC) alone, or combination with bethanechol chloride has been generally accepted as treatment modality. Until presently, bethanechol chloride is the only pharmacologic agent commonly used for bladder emptying without significant complication. However, the effectiveness of bethanechol seem to be episodic. The present study compared the contractile response of various pharmacologic agents including bethanechol chloride, ATP, PG E1, E2, F2-alpha on the smooth muscle strips of male rabbit bladder. In addition, effect of the gastrointestinal motility agents such as cisapride and metoclopramide on the contraction of rabbit bladder were assessed. Each bladder was divided into bladder body and bladder base for comparison of pharmacologic effects. FS at basal tension elicited a frequency dependent contraction which was greater in bladder body strips than in bladder base strips. The contractile responses to bethanechol, ATP, PG E1, E2 and PG F2-alpha were greater in bladder body than in bladder base.In the bladder body,magnitude of the contractile responses by ATP and PG F2-alpha were approximately 1/3 of those by bethanechol or FS.PG F2-alpha was consistently more potent to produce contraction than PG E1, E2. ATP induced contraction only consisted of initial phasic rise of tension. The contraction induced by PG developed slower than those caused by bethanechol. Cisapride(10uM) induced weak contractile responses comparable to those by PG E1 Metoclopramide had no contractile effects in this studies. Conclusively, differences exist in the response of the bladder body and base to FS and various pharmacologic agents. ATP, PG E2 and PG F2-alpha exhibited some notable contractile responses to the bladder body that were approximately 1/3 of those by bethanechol. Gastrointestinal motility agents were not shown to be effective in the mediation of contraction of rabbit bladder.