[Microcirculation in the liver in normal blood oxygenation and hypoxemia]

Vital contact microscopy and microfilming were used to measure the blood flow velocity in hepatic sinusoids 11 +/- 1 microns in diameter. The white blood cells moving in the axis stream of the red cells were used as the markers to measure linear flow velocity. In normoxia it was equal to 0.29 +/- 0.01 mm/sec and the volumetric flow rate in a liver sinusoid as calculated from this value was about 1.65 . 10(-3) microliters/min. Breathing with the mixture of nitrogen and 7% oxygen evoked a decrease of arterial blood pressure down to 80-70 torr and oxygen tension in a. femoralis and v. porta down to 45 +/- 3 torr and 18 +/- 3 torr, resp., as compared with 77 +/- 3 and 41 +/- 2 torr in normoxia. The mean sinusoidal blood flow velocity increased by nearly 12% only (p less than 0.01). This suggests that the increased oxygen extraction is the main compensatory mechanism in liver tissue hypoxia.