Effects of Rhynchophylline on relaxation and contraction of the bladder detrusor in rats

H.-M. Jiang, D.-W. Fu, L.-E. Zang, S.-B. Si, B. Song

Department of Urology Surgery, The First Affiliated Hospital of Liaoning Medical College, Jinzhou, China. huamaojiang@163.com

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• Urology

AIM: The aim of this study was to observe the effects of Rhynchophylline (Rhy) on the relaxation and contraction of rat bladder detrusor and urodynamics and determine the changes in the tension of isolated rat bladder muscle strips.

MATERIALS AND METHODS: Rats were randomly divided into four groups: sham-operated, overactive bladder (OAB) model, Rhy-treated, and the control group. Sections of urodynamic testing and electrophysiological OAB indicators of detrusor were measured. The effect of tension on the isolated rat bladder detrusor muscle strips was determined; activators and antagonists of calcium-activated potassium ion channels were detected in vitro using the tension method. The contraction of detrusor muscle strips and the antagonism of acetylcholine due to changes in muscle contraction were observed.

RESULTS: The Rhy-treated group significantly decreased the maximum bladder capacity, bladder filling pressure, leak point pressure, contraction frequency, motility index (p < 0.05). The affinity index of Rhy was 4.53 ± 0.22. However, 1 µmol/L to 2 μmol/L Rhy shifts CaCl2 cumulative dose-response curves to the right in a non-parallel manner, showing a non-competitive antagonism. Rhy inhibits detrusor contraction by blocking L-type calcium channels and activating big-conductance calcium-activated potassium channels. A low concentration of Rhy can inhibit muscle contraction caused by intracellular calcium.

CONCLUSIONS: Rhy plays an important role in OAB treatment and decreases effectively on sections of urodynamic testing and electrophysiological OAB indicators of detrusor.

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