pO/sub 2/-dependent regulation of microvascular blood flow in skeletal muscle

The pO/sub 2/-dependent regulation of microvascular blood flow was evaluated in rabbit skeletal muscle in vivo. The tenuissimus muscle was prepared to observe the microcirculation. The mean red blood cell velocity and perfused capillary density at various tissue pO/sub 2/ levels were measured using an intravital video-microscope. Both velocity and density were significantly decreased as tissue pO/sub 2/ was elevated, but the relationship between capillary flow and tissue pO/sub 2/ was not a linear correlation. In addition, the critical pO/sub 2/ value effected on microvascular blood flow regulation may exist in the tissue pO/sub 2/ ranging from 30 to 50 mmHg, which might be detected in the region of arteriolar walls.