Mechanisms for nitrite loss from the stomach.

摘要: Nitrite loss from the stomach was studied using dogs equipped with Thomas cannulas for direct access to lumen. Solutions containing sodium nitrite and non-absorbable volume marker (polyethylene glycol, PEG) were infused into stomach, samples taken over 60 min determine concentration of 'total nitrite' (including NO2-, HNO2 other species in equilibrium NO2-) rate dilution contents as a function time. Changes also measured. found be very rapid, total concentrations declining less than half initial levels 10 min. The decay due predominantly gastric absorption, small additional contributions (inferred PEG concentrations) chemical reactions (from vitro kinetic data). Results varying range 0.15-4.5 mM showed absorption first order nitrite. permeability-area product (PA) about 0.6 l/h, unaffected by addition 1 SCN- or Cl-. All these results are consistent form NO2- HNO2. Buffering infusate HCO3- increase luminal pH approximately 2 7 caused three-fold reduction apparent value PA. When pentagastrin used stimulate acid secretion, only fast when secretion inhibited cimetidine, no drug given. This effect could not explained variations pH, suggests that either decreases PA is accompanied active Based on data, mathematical model developed physical factors governing stomach.