Syt1^M3 bladder strips are less sensitive to BoNT/B than WT bladder strips.

A. Contractile responses to electrical field stimulation of WT and KI mice, in the setting of high dose (1 nM) of BoNT/B. WT and Syt2^M3 bladder strips have decreased contractile capability, while Syt1^M3 bladders are largely resistant to the effect of BoNT/B. Only under long duration (300 mins) of 1 nM BoNT/B do Syt1^M3 bladders begin to become slightly paralyzed. B. Carbachol treatment validates that bladder muscle viability and contractility remain unchanged after incubation with high dose BoNT/B. C. Survival curve for direct bladder wall injection of BoNT/B revealed the highest tolerable dose injected into the bladder is 3.25 pg. Systemic toxicity and death resulted from 4.25 pg bladder injection. WT 1 nM BoNT/B (n = 2); Syt1^M3 1 nM BoNT/B (n = 5); Syt2^M3 1 nM BoNT/B (n = 5).

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