Transport of potassium-42 from blood to tissue in isolated mammalian skeletal muscles

A method is described for studying transcapillary diffusion of K 42 in isolated perfused muscles of dogs. Blood flow and arteriovenous K 42 differences are measured and blood-tissue clearance calculated by the Fick principle. A theoretical relation between blood flow and blood-tissue clearance is developed for a uniform circulation characterized by a constant permeability—surface area product (PS). The experimental observations conform reasonably closely to prediction. However, systematic variation in measured PS product with changes in blood flow and vascular resistance indicate that the capillary circulation is not uniform.