Figure 4.

APD₉₀ widening by terikalant is positive rate-dependent and increases with a decrease in cycle length, at cycle lengths between 550 and 300 ms. When the cycle length duration was similar in value to the APD₉₀ value (<300 ms CL), there was a gradual reduction in the effect of terikalant. (a) Steady state APD₉₀ plotted against cycle length in the presence and absence of 10 μM terikalant for one ventricular myocyte. (b) Per cent prolongation of steady state APD₉₀ by 10 μM terikalant for a range of cycle lengths. The data shown is an average of four cells. At cycle lengths greater than 475 ms, there was an apparent shortening of APD₉₀ in some cells, in the presence of terikalant.