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OBJECTIVE: To assess the functional role of Hyperpolarization-activated cyclic nucleotide-gated gated channel (HCN) subtypes in the aging bladder phenotype characterized by diminished bladder volume sensation (BVS) with or without the detrusor instability (DI). METHODS: Expression of HCN subtypes was examined by quantitative RT-PCR and Western blot in aged male Fisher 344 rats (n=15) and young rats (n=15). Nocturnal urination and awake cystometry (CMG) were assessed in presence and absence of a steady state HCN channel blockade achieved with daily oral gavage of vehicle or Ivabradine (HCN blocker) 6mg/kg for 7 days. RESULTS: The association of BVS with the age-related downregulation (~30%) of cAMP sensitive HCN1, HCN2 subtypes, and (~50%) upregulation of cAMP insensitive HCN3 subtype is evinced by a doubling in the mean urine volume of nocturnal voids (0.82 ±0.22 mL vs 0.41 ±0.12 mL; n=10; p < 0.05) predicting an age-related rise in micturition volume threshold (p

OBJECTIVE: To evaluate whether approved gastroprokinetic agent, acotiamide exerts a direct excitatory effect in bladder to help explain the reported meaningful reduction of post-void residual urine volume (PVR) in detrusor underactivity (DU) patients after thrice daily oral intake of acotiamide 100 mg for 2 weeks. METHODS: Effect of acotiamide [1–16μM] was assessed on nerve-mediated contractions evoked by electrical field stimulation (EFS) for 5s with 5ms pulse trains of 10V in longitudinal, mucosa intact rat and human bladder strips to construct frequency response curve (1–32Hz) and repeat 10Hz stimulation at 60s interval. Effect of acotiamide 2μM on spontaneous and carbachol evoked contractions was also assessed. RESULTS: Acotiamide 2μM significantly enhanced the Atropine and Tetrodotoxin (TTX)-sensitive EFS evoked contractions of rat and human bladder at 8–32Hz (Two-way ANOVA followed Sidak’s multiple comparison; *p