Activation of α1D Adrenergic Receptors in the Rat Urothelium Facilitates the Micturition Reflex

Purpose: Previous studies have revealed that the activation of α1 adrenergic receptors in urothelial cells releases neurotransmitters. We determined if α1D adrenergic receptors are expressed in the urothelium of the rat bladder and if inhibition of these receptors affects reflex voiding.Materials and Methods: Female Wistar rats were used in the experiments. Receptor expression was evaluated by Western blot. The effects of receptor activation were studied using cystometrograms, measurement of adenosine triphosphate concentrations in the bladder lumen and afferent nerve recording. The α1D antagonist naftopidil (0.75 to 1.66 mg/kg) was administered intravenously into the external jugular vein.Results: The expression of α1D adrenergic receptors was detected in urothelial tissue with Western blot and immunohistochemistry. The α1D receptor antagonist naftopidil prolonged the intercontraction interval during continuous infusion cystometrograms in conscious rats (143% of the control value) and suppressed the exci...