Effects of topical isoproterenol on bile acid-induced gastric mucosal injury.
Topical isoproterenol protects the gastric mucosa from the severe necrosis induced by 100 per cent ethanol. Its effect on gastric mucosal blood flow is unknown. The purpose of this study was to determine the effect of topical isoproterenol on gastric mucosal blood flow and on the less severe gastric mucosal injury caused by dilute bile acid. Prior to injury with topical 5 mM acidified taurocholate (pH 1.2), stomachs were pretreated with either saline or isoproterenol (low dose = 50 micrograms/kg; high dose = 500 micrograms/kg). Mucosal injury was assessed by measuring net transmucosal ion fluxes (H, K) and the appearance of DNA into the gastric lumen (DNAE). Gastric mucosal blood flow was determined by using laser doppler. Pretreatment with isoproterenol significantly decreased bile acid-induced net transmucosal ion fluxes and luminal accumulation of DNA, suggesting mucosal protection. Furthermore, this effect was dose-dependent on H and DNAE but not K. Pretreatment with topical high dose isoproterenol had no significant effect on gastric mucosal blood flow. Thus, topical pretreatment with isoproterenol dose dependently protects the gastric mucosa from the superficial injury caused by the application of dilute bile acid. This protective effect appears to be mediated by a mechanism other than augmentation of gastric mucosal blood flow.
Mercer
D W
DW
Reichel Research Laboratory, Department of Surgery, Temple University Hospital, Philadelphia, Pennsylvania 19140.
Podolsky
R S
RS
Ritchie
W P
WP
Dempsey
D T
DT
D000287:Administration, Topical; D000818:Animals; D004247:DNA / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D005753:Gastric Mucosa / Q000098:blood supply / Q000737:chemistry / Q000187:drug effects* / Q000473:pathology / Q000503:physiopathology; D006863:Hydrogen-Ion Concentration; D007545:Isoproterenol / Q000008:administration & dosage / Q000627:therapeutic use*; D017078:Laser-Doppler Flowmetry; D011188:Potassium / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow / Q000187:drug effects; D013656:Taurocholic Acid / Q000009:adverse effects*
D013656:Taurocholic Acid; D004247:DNA; D007545:Isoproterenol; D011188:Potassium