Relation between venous pressure and blood volume in the intestine

¹ Department of Physiology and the Heart Research Center, Indiana University School of Medicine, Indianapolis, Indiana

The pressure volume characteristics of the intestinal venous vasculature were studied in vivo by a weight technique. The pressure-volume relationship was linear over the range 0–20 mm Hg. In a few experiments the volume increment appeared to be reduced at venous pressures above 30 mm Hg. The average compliance of the intestinal veins was 0.34 ml/mm Hg 100 g tissue. The time course of the blood volume change was also examined. Rapid elevation of venous pressure to a higher level caused blood volume to increase at an exponentially declining rate. Therefore, the phenomenon of creep in the intestinal veins appears to be a simple exponential process. The half time of the increase in venous volume averaged 7.5 sec while the time constant was 10.9 sec. The magnitude of the time constant suggests the presence of elements of rather high viscosity in the venous wall.