Kinetics study of chloride in rat.

The kinetics of chloride were studied in Sprague-Dawley rats following the oral administration of Na36Cl. The half-life for 36Cl- absorption from plasma was 19.2 h corresponding to a rate constant of 0.0361 h-1, while the half-life for 36Cl- elimination from plasma was 51.9 h, corresponding to a rate constant of 0.0134 h-1. At 120 h, radioactivity was highest in plasma, followed by kidney, lung, stomach, and spleen, and the lowest activity was observed in fat. Plasma and packed cells contained almost the same concentration of 36Cl-. Plasma protein binding of chloride was significantly higher than liver protein binding. Subcellular distribution in liver fractions revealed that most of the 36Cl- was located in the cytosolic fraction. The excretion of chloride occurred primarily by the kidney.