Effect of local acid-base status on gastric mucosal blood flow and surface cell injury by bile acid.
Topical application of 5 mM sodium taurocholate (5 TC, pH 1.2) to canine gastric mucosa results in luminal hydrogen ion (H+) loss and surface epithelial cell (SEC) injury. However, gross mucosal injury does not occur because of a protective increase in gastric mucosal blood flow (GMBF). The mechanism of this blood flow response is unknown. To test the hypothesis that mucosal acid-base status influences mucosal blood flow and surface cell injury, three groups of dogs with vascularized chambered gastric mucosae were studied during two sequential 30-min periods. Mucosae were exposed during period I to topical acidified isotonic saline (ATS, pH 1.2), and during period II to topical 5 TC. During both periods, group A (n = 5) received close intraarterial (ia) NaCl (0.15 M), group B (n = 5) close ia HCO3 (0.32 M), and group C (n = 4) close ia HCl (0.2 N). Parameters evaluated during both ATS and 5 TC periods included the luminal accumulation of DNA (DNAE, a sensitive marker of SEC exfoliation), luminal H+ loss, and GMBF measured using radiolabeled microspheres. Gastric venous pH was also measured. It was found that, compared to the NaCl group, the HCO3 group had no increase in GMBF after 5 TC exposure. Simultaneously, however, SEC loss was reduced by 48%, 604 +/- 72 with NaCl versus 314 +/- 59 micrograms/30 min DNA with HCO3, P < 0.025. Infusion of ia HCl generated a large increase in GMBF without an increase in SEC injury compared to ia NaCl. Thus, mucosal acid-base status is an important modulator of mucosal blood flow which is itself critically important to gastric mucosal protection during bile acid induced injury.
Sullivan
T R
TR
Department of Surgery, Temple University School of Medicine, Philadelphia, Pennsylvania 19140.
Dempsey
D T
DT
Milner
R
R
Ritchie
W P
WP
D000136:Acid-Base Equilibrium; D000818:Animals; D001639:Bicarbonates / Q000008:administration & dosage; D001769:Blood; D001783:Blood Flow Velocity; D004285:Dogs; D004848:Epithelium / Q000187:drug effects; D005745:Gastric Acidity Determination; D005753:Gastric Mucosa / Q000098:blood supply* / Q000187:drug effects; D006851:Hydrochloric Acid / Q000008:administration & dosage; D006863:Hydrogen-Ion Concentration; D013276:Stomach Ulcer / Q000139:chemically induced*; D013656:Taurocholic Acid / Q000494:pharmacology*
D001639:Bicarbonates; D013656:Taurocholic Acid; D006851:Hydrochloric Acid