(A) The measured excitation thresholds and (B) maximum capture rates for scaffolds stimulated at various levels in culture. There is a decrease in excitation threshold accompanying increasing levels of electrical stimulation, although at stimulation levels above 8 V/cm, there was some observed lack of contraction, suggesting that there is an optimal level of stimulation below this level. Maximum capture rates also increased for stimulation levels less than 5 V/cm, but decreased for stimulation at 8 V/cm, and then at levels above this scaffolds would not contract, again suggesting that optimal stimulation levels are below 8 V./cm (n = 3–5 samples per condition).