• T Kutsuzawa and H Yamabayashi.
• Second Department of Internal Medicine, School of Medicine, Tokai University, Isehara.
• Tohoku J. Exp. Med. 1988 Mar 1; 154 (3): 305-14.

AbstractChange in mixed venous oxygen tension (PVO2) during transition from rest to exercise induced by rhythmic contractions of the hindlimb of dogs was continuously monitored using intravascular oxygen electrodes. The rapid fall in PVO2, on the average 9.5 sec after the onset of rhythmic contraction, was found. The time course of change in PVO2 was not altered by ligation of the splenic artery and vein. Oxygen tension of venous blood in the superior vena cava and the inferior vena cava was monitored in order to elucidate the mechanism of rapid fall in PVO2 following induced exercise. Oxygen tension of venous blood in the superior vena cava did not fall at the onset of contraction. Oxygen tension of venous blood in the distal and proximal end of the inferior vena cava began to fall at 4.4 sec and at 6.9 sec after the onset of contraction on the average, respectively. There was no significant difference between the hematocrit of mixed venous blood at rest and after 15 sec of exercise. These findings suggest that the rapid fall of PVO2 results from a surge of low oxygenated blood from the exercising hindlimb and that this change in blood gas tensions possibly reaches the lung within 10 sec after the onset of exercise.

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