ABSTRACT
We examined the effects of alpha-adrenergic blockade (phentolamine) and intestinal denervation on the circulatory response of the newborn swine intestine to severe arterial hypoxia. Intestinal vascular resistance significantly increased during severe arterial hypoxia in the control group, whereas no change in intestinal vascular resistance was observed in the phentolamine or denervation groups at this time. Intestinal perfusion pressure increased in the control group but decreased in the phentolamine and denervation groups during severe arterial hypoxia. Despite the difference in intestinal vascular resistance, intestinal blood flow decreased in a similar manner in all groups during severe arterial hypoxia. Intestinal arteriovenous O2 content difference [(a-v)O2] and O2 uptake were greater during severe arterial hypoxia in the phentolamine and denervation groups than in the control group. We speculate that the sympathetic stimulation mediates the increase in intestinal vascular resistance in newborn swine during severe arterial hypoxia; and sympathetic stimulation limits the increase in intestinal (a-v)O2, which occurs during severe arterial hypoxia in the newborn swine intestine.
