The feasibility and validity of endoscopic measurements of gastric mucosal blood flow (GMBF) using 3% H2 gas clearance were investigated in the intact stomach of anesthetized dogs. Platinum electrodes were lengthened and modified to permit passage through the instrument channel of a standard gastroscope. In five anesthetized dogs, antral mucosal blood flow (103.2 ± 5.3 ml/min/100 g tissue) was significantly higher (P < 0.05) than that in the corpus (66.9 ± 7.1 ml/min/100 g tissue). Histamine stimulation selectively increased flow in the corpus to 134.5 ± 7.5 ml/min/100 g tissue. Comparison of endoscopic GMBF measurements in these five dogs on 2 different days revealed a close correlation (r = 0.87, P < 0.001). Endoscopic H2 clearance measurements obtained in five awake dogs were not significantly different from those obtained during pentobarbitol anesthesia. In 12 dogs, GMBF determined by endoscopic H2 gas clearance showed a good agreement (r = 0.91, P < 0.001) 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 3% H2 gas clearance can be used to accurately and reproducibly measure GMBF through the endoscope, a unique advantage of this method for potential clinical use.
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