The role of acid and ischemia in production of stress ulcers during canine hemorrhagic shock

Hemorrhage to a mean arterial pressure of 41 mm. Hg in ten dogs decreased Heidenhain pouch blood flow to 6 ml. per minute and aminopyrine clearance to 0.93 ml. per minute. Pouch oxygen consumption fell from 1.47 to 0.74 ml./min. · 100 Gm. and total body oxygen consumption remained unchanged. Net ion fluxes during shock and reinfusion did not change significantly from control values of -89.8 μEq./30 min. · 100 cm.² for H⁺ and 88.6 μEq./30 min. · 100 cm.² for Na⁺. However, PD decreased from 54 to 24 mv. in parallel with a fall in net Cl^- flux from 56.8 to -11.7 μEq./30 min. · 100 cm². Nine of ten pouches subjected to shock and instilled acid test solution (ATS) developed superficial mucosal erosions. No ulcerations were found in either seven control dogs (anesthesia + ATS) or in three dogs subjected to shock without ATS. Acid appears to be of prime importance in the production of stress ulcers during or following ischemia, even though there is no increase in mucosal ionic permeability.