Oxygen Consumption of Arterioles and Venules as Studied in the Cartesian Diver

1. The Cartesian diver microrespirometer has been applied to the measurement of oxygen consumption by mesenteric arterioles and venules from hamsters and human beings. Oxygen consumption by the smallest arterial vessels, less than 150 μ in diameter, averaged 1.05 μliter/mg/hr, in contrast to only 0.58 μliter/mg/hr for arteries 250 to 400 μ in diameter. Hamster venules consumed oxygen at an average rate of 0.53 μliter/mg/hr, nearly equal to the largest arteries studied. Venous oxygen consumption did not vary with vessel diameter. 2. Both arterioles and venules were highly resistant to hypoxia, maintaining normal rates of oxygen uptake at environmental oxygen tensions as low as 12 mm Hg, but not at 5 or 2 mm Hg. Veins consumed less oxygen at an environmental pO2 of 150 mm Hg than at 57, 28, or 12 mm Hg, whereas arterial QO2 was unchanged between 12 and 150 mm Hg. 3. Ten human mesenteric arteries, 65 to 175 μ in diameter, and 10 human veins, 130 to 450 μ in vitro, had average rates of oxygen consumption of 0.35 and 0.25 μliter/mg/hr, significantly lower than hamster vessels. 4. Vessels from hamsters sacrificed without anesthesia consumed oxygen at rates similar to arterioles and venules removed from animals under pentobarbital anesthesia.