Capillary filtration coefficient in the canine hindpaw at different levels of venous pressure.

Capillary filtration coefficient (CFC) was determined in 12 dog's hindpaw preparations following elevation of venous pressure. From the quotient of slow component tissue volume change divided by the change in capillary pressure, the CFC averaged 0.027, 0.028 and 0.038 ml/min/mm Hg/100 gm respectively with an elevation of venous pressure from 0 to 15, 30 and 45 mm Hg. As compared with the previous determinations of CFC in the other tissues, the CFC of canine hindpaw was approximately in the same order of magnitude as that of the hindlimb, and was much less than those of the lung, intestine and heart. At venous pressure below 30 mm Hg, the CFC did not alter significantly with the level of venous pressure. This finding indicated that neither "stretched pore phenomenon" nor myogenic sphincter constriction occurred in response to a moderate increase in intramural pressure. The slight increase in CFC when venous pressure was elevated to 45 mm Hg suggested slight change in capillary permeability at high venous pressure, presumably due to the presence of stretched pore phenomenon.