Organ blood flow, cardiac output, arterial blood pressure, and vascular resistance in rats exposed to various oxygen pressures.

Blood flow in different organs, cardiac output, and arterial blood pressure were measured in unanesthetized rats under 1, 2, 3.5, 5, and 7 ATA O2, during first electrical discharge developed at 7 ATA O2 and following decompression. Brain, spinal cord, and hypophysis blood flow were reduced after 10 min of exposure to 2, 3.5, and 5 ATA O2 and were normal before and during first electrical discharge. Liver and muscle blood flow were significantly reduced under all investigated pressures, while myocardium, lung, kidney, and adrenal blood flow remained unchanged except for a significant increase in myocardium and lung blood flow under 1 ATA O2. Cardiac output was significantly decreased while arterial blood pressure was significantly decreased under all investigated pressures. The total peripheral resistance increased 36 to 81% at various oxygen pressures. These results are discussed in relation to the possible involvement of hemodynamic changes in awake animals, in the development of the adverse effects of HOP.