Continuous monitoring of gastroduodenal mucosal hemodynamics in rats by laser-Doppler flowmetry and reflectance spectrophotometry.

Gastroduodenal mucosal hemodynamics in rats was monitored continuously by laser-Doppler flowmetry (LDF) and reflectance spectrophotometry, and the validity of these techniques was determined. Corpus mucosal hemodynamics was recorded for 90 min, under stable conditions. In cases of graded hemorrhagic hypotension, corpus mucosal blood flow by LDF and hydrogen gas clearance, and potential differences showed a good correlation. Corpus, antral, and duodenal mucosal hemodynamics monitored by LDF, hydrogen gas clearance, and reflectance spectrophotometry reflected regional hemodynamic differences. In monitoring mucosal hemodynamics by LDF and reflectance spectrophotometry, regular oscillations (4-6 cycles/min) were observed in most animals. The characteristic change of oscillations during graded hemorrhagic hypotension was thus elucidated. In moderate hypotension (50-90 mmHg), high-amplitude and high-frequency (5-10 cycles/min) oscillations were observed, while in cases of severe hypotension (25-40 mmHg), the oscillations almost ceased. Observation of the oscillatory changes is thus a new application of LDF and reflectance spectrophotometry.