The present study was performed on eight young pigs to test the hypothesis that glucagon increases hepatic oxygen supply to a greater extent than hepatic oxygen uptake, providing a better hepatic oxygen supply-demand relationship. The experiments were performed under pentobarbital sodium anesthesia and controlled ventilation. Splanchnic blood flow was studied using radioactive microspheres. Glucagon was administered in doses of 1 and 5 micrograms X kg-1 X min-1. During glucagon infusion, hepatic arterial blood flow substantially increased, splenic and pancreatic blood flows increased moderately, while stomach and intestinal blood flows, as well as portal blood flow did not change significantly. Shunting of both 9- and 15-micron spheres through preportal tissues did not change significantly. Oxygen content in arterial or portal venous blood did not change significantly, while it increased in hepatic venous blood by 30%. There were no differences in the effects between the doses of glucagon administered. There was no correlation found between changes in hepatic oxygen supply and cardiac output or blood pressure. The changes observed during glucagon administration resulted in an increase in oxygen delivery to the liver and hepatic oxygen supply-uptake ratio.

Animals↗

PubMed1987

Hepatic circulation during surgical stress and anesthesia with halothane, isoflurane, or fentanyl.

Hepatic blood flow and the oxygen supply/uptake relation were studied in 19 miniature pigs using labeled microspheres. Changes in hepatic arterial blood flow and portal blood flow, as well as total hepatic blood flow during halothane anesthesia were more closely associated with changes in mean arterial pressure (MAP) and cardiac output than during anesthesia with isoflurane or fentanyl. Halothane or isoflurane administered in concentrations that decreased MAP by approximately 30% were accompanied by decreases in hepatic oxygen delivery (DO2th) averaging 46% during halothane and 31% during isoflurane anesthesia and parallel decreases in hepatic blood flow. In concentrations that decreased MAP by 50%, halothane and isoflurane decreased DO2th 61 and 37%, respectively. DO2th was maintained (statistically insignificant, 23% increase) during both doses of fentanyl administered (20 micrograms/kg followed by 0.17 microgram . kg-1 . min-1, and 50 micrograms/kg followed by 0.42 microgram . kg-1 . min-1). Hepatic oxygen uptake increased 50% during fentanyl and was maintained at baseline levels during both doses of halothane and isoflurane anesthesia. Oxygen content in hepatic venous blood was maintained at baseline levels during fentanyl and isoflurane administration and was decreased by both concentrations of halothane anesthesia. The hepatic oxygen supply demand ratio was maintained at baseline levels after both doses of fentanyl and during isoflurane administered in a concentration that decreased blood pressure 30%; the ratio decreased during isoflurane administered in a concentration decreasing blood pressure by 50% and during both doses of halothane anesthesia.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗