Regional distribution of blood flow during mild dynamic leg exercise in the baboon

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Abstract
Five chair-restrained baboons were trained with operant techniques and a food reward to perform dynamic leg exercise. Cardiac output and blood flows to most tissues were determined by radioactive microsphere distribution. After 2 min of exercise mean arterial blood pressure had increased by 11 .+-. 3% (SE), heart rate by 34 .+-. 7%, cardiac output by 50 .+-. 12% and O2 consumption by 157 .+-. 17%. Blood flow to exercising leg muscle increased by 585 .+-. 338% and to the myocardium by 35 .+-. 19%. Blood flow to torso and limb skin fell by 38 .+-. 4 and 38 .+-. 6%, respectively, and similar reductions occurred in adipose tissue blood flow. Nonworking skeletal muscle blood flow decreased by 30 .+-. 10%. Renal blood flow was lowered by 16 .+-. 2%. The lower visceral organs had more variable responses, but when grouped together, total splanchnic blood flow fell by 21 .+-. 9%. Blood flow to the brain was unchanged with exercise; spinal cord perfusion increased 23 .+-. 3%. During short dynamic exercise, baboons redistributed blood flow away from skin, fat, nonworking muscles and visceral organs to supply the needs of exercising muscles. The baboon is a useful animal model for investigating vascular responses of tissues, such as torso skin, adipose, individual visceral organs and the spinal cord, that cannot be examined in humans.