AJP - Gastrointestinal and Liver Physiology, Vol 247, Issue 4 339-G345, Copyright © 1984 by American Physiological Society
Measurements of gastric mucosal blood flow by hydrogen gas clearance
S. W. Ashley and L. Y. Cheung
The validity of the use of H2 gas clearance to measure gastric mucosal
blood flow (GMBF) was investigated in the intact stomach of anesthetized
dogs. With a modified, more sensitive platinum electrode, we were able to
reduce the H2 gas concentration to a nonflammable gas mixture. GMBF was
repeatedly measured when the dogs inhaled gas containing 100, 10, and 3-5%
H2. GMBF measured using 100% H2 demonstrated close correlation with inhaled
gases containing 10% H2 (r = 0.84, slope = 0.89) and 3-5% H2 (r = 0.91,
slope = 0.88). At a nonflammable concentration of 3% H2, it was safe to add
20% O2 into the gas mixture. The addition of O2 into the inhaled gas
eliminated the transient hypoxia noted otherwise. It was also possible to
reduce the gas flow rate from 5-10 to 1-3 l/min. Regression analysis of
GMBF determined by inhalation of 5% H2 at these flow rates revealed a
significant linear correlation (r = 0.95, slope = 1.13). In 10 dogs GMBF
determined by using these low concentrations of H2 at the low flow rates
also showed a good agreement (r = 0.93, slope = 0.65) with that measured by
radioactive microspheres. These two methods also demonstrated comparable
changes in GMBF induced by intravenous infusion of histamine and
vasopressin. It was concluded that, with the technique as modified in our
laboratory, H2 gas clearance could be a safe and accurate tool for
quantitating gastric mucosal blood flow.
