Regional blood flow in newborn piglets during environmental cold stress

Regional blood flow, oxygen delivery, and vascular resistance were determined in newborn piglets during a successful homeothermic response to environmental cold stress. Eight 3- to 4-day-old awake piglets were studied in a thermoneutral environment and 30, 45, and 60 min after onset of environmental cold stress. During cold stress, blood flow was significantly increased to skeletal muscle, the thermogenic organ, and decreased to the small intestine (P less than 0.05). Because arterial oxygen content (CaO2) was stable during the study, changes in oxygen delivery (CaO2 X blood flow) paralleled blood flow. Vascular resistance during cold stress was significantly decreased in skeletal muscle and increased in both the adrenals and the small intestine (P less than 0.05). We conclude that, during successful thermogenesis, the redistribution of cardiac output toward the thermogenic organ (skeletal muscle) is associated with a significant decrease in intestinal blood flow and oxygen delivery. This is not a passive process as evidenced by the coincident observation of increased intestinal vascular resistance.