Arterial and venous pressure-resistance relationships in perfused leg and intestine

¹ Civil Aeromedical Research Institute, Federal Aviation Agency, Oklahoma City, Oklahoma

Pressure-resistance relationships in the kidney have been previously characterized in this laboratory. The purpose of the present investigation was to extend the scope of these previous studies to include tissues other than the kidney. A series of 16 experiments was carried out on the isolated leg and intestine. Organs were perfused at constant pressure by means of a Starling shunt device. Small-vein pressures were determined, and changes in organ weight were continually monitored. Care was taken to achieve an adequate experimental preparation by meticulous ligation of severed vessels and tissues other than the orifice vein. Arterial pressure was increased in a stepwise manner through a wide range. Resistances fell as a function of a rise in perfusion pressure in all instances in leg and intestine preparations. Elevations in small-vein pressure were significantly less than those previously found in the kidney under identical experimental conditions. Results emphasize the similarity of resistance changes in the leg and intestine in contrast to those observed in the kidney.