Effect of magnesium on the contraction of whole rabbit bladder in vitro.

Smooth muscle function, including that of the bladder, is mediated by changes in the intracellular concentration of calcium. Magnesium modulates the transport of calcium and may modify bladder function. This study was designed to investigate the effect of magnesium on the response of rabbit whole bladder to field stimulation in vitro. The response to field stimulation was decreased by magnesium in a concentration-dependent manner. Verapamil significantly enhanced the suppressive effect of magnesium, whereas BAY-K8644 decreased the effect of magnesium. The detrusor response to field stimulation was not changed by increased osmolarity. Results suggest that magnesium reduced the intramural nerve-stimulated contraction of rabbit whole bladder by a mechanism involving L-type calcium channels.