AJP - Regulatory, Integrative and Comparative Physiology, Vol 251, Issue 5 887-R892, Copyright © 1986 by American Physiological Society
Hepatic splanchnic function in acutely hypoxemic humans at rest
J. R. Blackmon and L. B. Rowell
Splanchnic metabolism of O2, glucose, and lactate was studied in five
normal men during rest while breathing air, 10.4% O2 [arterial O2 partial
pressure (PaO2) = 34.8 Torr], and in four men breathing 7.6% O2 (PaO2 =
27.0 Torr). Despite reduction in arterial O2 content to 10.7 ml/100 ml,
splanchnic O2 uptake (VO2) and arteriovenous O2 difference remained
constant through a fall in hepatic venous O2 content to 7.3 ml/100 ml.
Hepatic release of glucose and uptake of lactate were unaffected by either
moderate or severe hypoxemia. In five other men hepatic extraction
efficiency, removal rate, and clearance of norepinephrine (NE) and
epinephrine (E) (radioenzymatic assay) were determined, while air and
10.27% O2 were breathed, and while NE was infused over widely ranging rates
(constant in a given subject). Over arterial concentrations of 1.8-17 ng/ml
for NE and 0.03-0.3 ng/ml for E, splanchnic removal was closely related to
arterial concentration and was unaffected by hypoxemia. NE extraction
efficiency rose from 60 (control) to 94% (during infusion in normoxia and
hypoxemia); E extraction efficiency remained constant at 85% under all
conditions. Hepatic clearances of both NE (556-824 ml/min) and E (630-804
ml/min) were unaffected by hypoxemia. The only observed deficiency in
hepatic function was a significant decrease in extraction of indocyanine
green in all 10 subjects at both levels of hypoxemia.
