Neurogenic function of the diabetic rat bladder: alteration by calcium channel effectors.

The in vitro effects of a calcium channel antagonist (nifedipine) and agonist (BAY K8644) on the neurogenic responses of the streptozotocin-induced diabetic rat bladder were investigated. The bladder body and bladder base were studied separately. There were no significant differences in neurogenic responses in diabetic bladder body compared to control body, but the diabetic bladder base demonstrated an increased contractile response at each frequency compared to control base. The rate of contractile response was similar in controls and diabetics but was significantly different between body and base. Although declining with time, contractile responses in the diabetic bladder body and base were increased from control in the absence of extracellular calcium. Differences were found in effects upon maximum responses between diabetic and control tissues treated with nifedipine and BAY K8644. BAY K8644 did not completely reverse the effect of nifedipine on the neurogenic responses in the diabetic bladder body. Effects of diabetes on the bladder body and base are associated with changes in calcium channel activity of bladder smooth muscle.