Calcium kinetics in individual heart segments.

The isolated, perfused rabbit heart was studied with reference to calcium decay and uptake in individual segments: atria, right ventricle, left ventricle, and septum. For each segment, calcium decay and uptake curves were obtained by direct tissue analysis for calcium. Fitting procedures established single exponential decay and single exponential uptake curves. Equilibrium values of calcium content that is, pre-washout and post-uptake calcium contents, followed the order: atrial greater than right ventricular greater than left ventricular = septal . Except for the atria, the uptake rate constant for each segment was significantly larger than the decay rate constant. While no significant trend could be found for exponential decay rate constants, uptake rate constants followed the order: septal greater than left ventricular greater than right ventricular greater than atrial.