Figure 5. The effects of ketamine on action potential duration, which was shortened by pinacidil. (A) A representative action potential profile of rat papillary muscle. The effects of ketamine on pinacidil-treated action potentials were recorded at a stimulation rate of 1 Hz. The horizontal line indicates 0 mV. (B) The averaged increases of action potential duration are shown for six observations obtained under the same experimental conditions as in Figure 5(A). Results are presented as means +/- SD. *Significantly different from control (P < 0.05).