Rate of Extravasation of Intravenously Injected Thiocyanate in the Dog

Abstract

The disappearance of thiocyanate from the blood was followed at 2-second intervals after single injection in anesthetized dogs. The cardiac output was calculated from the first periodic portion of the curve and the vascular clearance from the first aperiodic portion. The vascular clearance averaged 75% of the available thiocyanate of cardiac output. The first aperiodic portion of the disappearance curve was succeeded by elevations of concentration suggesting a return of previously cleared thiocyanate to circulation. Thiocyanate leaves the vascular system in bulk and its return is not visible for about 60 seconds after injection. It is suggested that this implies that 3/4 of filterable components of plasma circulate in bulk outside the vascular endothelium.