Kinetics of the red cell washout from coronary vessels of isolated feline hearts.

Twenty seven isolated feline hearts were perfused with cell-free oxygenated Ringer-Locke solutions. The concentration of red blood cells in samples of venous outflow collected from the coronary sinuses was determined by means of a Celloscope counter. Cellular concentrations decreased gradually as the perfusion time increased, and from 10(9) to 10(5) cells per millilitre after 300 ml perfusion. When the ventricular lumens were filled with residual blood (group I, 15 cats), several red cell peaks were superimposed on the smooth exponential decay curve of red cell washout. It is suggested that the peaks were caused by ejection of red cells from the ventricular lumens into communicating branches between the ventricular lumens and coronary capillaries. In cases of blood-emptied hearts (group II, 12 cats) these peaks did not occur, and mathematical analysis showed that summing three exponential functions could approximate the whole washout curve of red cells. This suggests that the coronary circulation may be described by three red cell compartments. The functional implication of this analysis for the microcirculation in the coronary vessels was discussed.