The effect of acid perfusion on mucosal blood flow and intramural pH of rabbit duodenum

To evaluate the role of blood flow for acid tolerance of the duodenal mucosa, we perfused the duodenums of anesthetized rabbits with different concentrations of hydrochloric acid (HCl). Acid perfusion stimulated blood flow to the duodenal wall in a concentration-dependent fashion up to 80 mmol/L HCl (0 mmol/L; 0.44 +/- 0.05, 10 mmol/L; 0.84 +/- 0.14, 50 mmol/L; 1.44 +/- 0.11, 80 mmol/L; 2.03 +/- 0.12, 100 mmol/L; 1.82 +/- 0.07 ml/gm/min X +/- SEM). The pH in the lamina propria of the mucosa, which was measured with antimony microelectrodes was not changed in experiments during perfusion with 50 and with 80 mmol/L HCl in normotension. Acidosis in the lamina propria could be demonstrated only when the duodenum was perfused with 100 and with 80 mmol/L HCl combined with hemorrhagic hypotension. Damage to the mucosa, which developed after 30 and 60 minutes of acid perfusion, also showed a H+-dependent pattern. Reduction of blood flow by hemorrhagic hypotension aggravated the morphologic damage. We conclude that luminal acid stimulates blood flow in the duodenum. The decrease in blood flow induced by hypotension results in a greater susceptibility to mucosal damage.