Gastric Venous Prostaglandin Concentrations during Basal and Stimulated Acid Secretion in Dog

Abstract

Abstract

A segment of canine gastric fundic in situ tissue was perfused at constant flow with femoral arterial blood. Plasma concentrations of 6-oxo-PGF_1α (the breakdown product of prostacyclin), PGE₂, and thromboxane B₂ (TXB₂) were measured in the gastric arterial and venous blood by radioimmunoassay. Under nonstimulated conditions, gastric venous plasma contained significantly higher levels of prostanoids than gastric arterial plasma, with 6-oxo-PGF_1α being predominant. Arachidonic acid markedly elevated TXB₂ levels in gastric arterial plasma and significantly elevated 6-oxo-PGF_1α and PGE₂ and TXB₂ levels in gastric venous plasma following administration into an arterial incubation coil leading to the stomach. However, no increase in gastric venous blood concentrations of 6-oxo-PGF_1α, PGE₂, or TXB₂ was observed during near maximal pentagastrin- or histamine-stimulated acid secretion. These observations suggest that while the endogenous prostanoids may be involved in the modulation of resting gastric blood flow, their role in mediating the gastric vasodilation associated with stimulated acid secretion is less clear.