PROSTAGLANDIN E-2 AND AGGRESSIVE FACTORS INCREASE THE GLAND LUMINAL PRESSURE IN THE RAT GASTRIC-MUCOSA IN-VIVO

Background & Aims: The gastroprotective properties of prostaglandins i n low concentrations are still unclear. In this study, we investigated the effects of prostaglandin E-2 (PGE(2)), indomethacin, and intralum inally applied HCl or ethanol on intraglandular pressure, mucus thickn ess, acid secretion, and gastric mucosal blood flow. Methods: Glandula r pressure and mucous gel thickness were measured with microelectrodes during intravital microscopy in thiobutabarbital sodium-anesthetized rats. Gastric blood flow was measured with laser Doppler flowmetry. Re sults: In pentagastrin-treated rats, glandular pressure increased sign ificantly in response to topical (1 mu g/mL) or intra-arterial (12 mu g.kg(-1).h(-1)) PGE(2) from approximately 17 to 69 and 18 to 57 mm Hg, respectively, whereas blood flow, mucus thickness, and acid secretion were unaltered. Indomethacin (3 mg/kg intravenously) significantly de creased glandular pressure from approximately 20 to 11 mm Hg. Intralum inal application of 10 and 100 mmol/L HCl or 20% and 40% ethanol signi ficantly increased glandular pressure but had no effect after indometh acin pretreatment. Conclusions: Endogenous PGE(2) is important for mai ntaining a high glandular pressure, and exogenous PGE(2) potently incr eases glandular pressure at concentrations not altering blood flow, mu cus thickness, or acid secretion. This suggests that high intraglandul ar pressures might be involved in gastroprotection.