Kinetic models for pressure response to volume change in tetanized isolated heart

Pressure responses to step changes in volume in the tetanized, isolated ferret heart were similar to tension responses to step changes in length in constantly activated, isolated cardiac muscle. It was hypothesized that kinetic models, homogeneous to those used to represent cross-bridge dynamics in muscle, would serve to represent pressure/volume dynamics in the LV chamber. Two models were investigated: one involving a single cyclic conversion of pressure generating units and another involving two cyclic conversions. These models were used to recreate observed pressure responses to both step and ramp changes in volume. It was found that the two-cycle model performed significantly better than the one-cycle model