We have designed a group of large conductance Ca2+ activated potassium (BK) channels agonists called the GoSlo-SR family (1) that may be useful in the future treatment of overactive bladder. We compared the effects of GoSlo-SR-5-6 with its deaminated form, GoSlo-SR-5-130 (Figure 1) on isolated rabbit bladder smooth muscle cells (RBSMC) and on BKα and β1 subunits expressed in human embryonic kidney (HEK) cells. Experiments were approved by DKIT Animal Care and Use Committee. Rabbits were killed with pentobarbitone (I.V.) and RBSMC isolated by enzymatic digestion. Experiments were performed at 37oC using excised inside/out patch configuration as detailed previously (1). All drugs were tested in 100 nM Ca2+ and were applied to the cytosolic face of the excised membrane patches. GoSlo-SR-5-130 (10 μM) negatively shifted the voltage required for half maximal activation of BK channels in RBSMC from 141±5 mV compared to 44±5 mV (p<0.05, paired t test, n=7). This shift (ΔV1/2) of -97±5 mV was not significantly different from the effect of the amine derivative GoSlo-SR-5-6 (-107±7 mV, n=12). To assess if the effects of GoSlo-SR-5-130 were altered by the presence of the β1 regulatory subunit, we expressed BK channels containing either the α subunit (HEKα or both α and β1 subunits (HEKαβ1) in HEK cells. GoSlo-SR-5-130 (10 μM) shifted the V1/2 from 160±3 mV to 67±5 mV (p<0.05, n=6) in HEKαβ1. In the absence of the β1 subunit, GoSlo-SR-5-130 only shifted the activation V1/2 from 185±3 mV to 145±5 mV (n=6). In conclusion, deamination of the C ring of GoSlo-SR-5-6 to form GoSlo-SR-5-130, produces a novel BK channel opener that is more efficacious on BKαβ1 channels than BKα channels.