Effect of prostaglandin E2 on the electrical activity of cat isolated stomach muscle

Prostaglandins (PGs) are believed to be present in the gastrointestinal tract and to increase the tone of longitudinal muscle layer. However the influence of PGs on the gastric slow wave (SW) is not clarified yet. We therefore investigated the effect of prostaglandin E₂ (PGE₂) on the electrical and the mechanical activities of feline isolated stomach muscle strips (7 × 1.5 cm), using five capillary electrodes (Ag-AgCl) and an isometric force transducer connected to the antral edge. One hundred and ninety-six strips, obtained from the corpus and antrum of 196 anaesthetized cats, were studied in a muscle chamber filled with Krebs solution (pH 7.4, temperature 36°C) bubbled with 5 % CO₂ in O₂. Exogenous PGE₂ concentration-dependently increased the gastric SW frequency without affecting the spike and mechanical activities. Indomethacin decreased the SW frequency. These responses to PGE₂ or indomethacin were not blocked by phentolamine, propranolol, hexamethonium, atropine or tetrodotoxin. It is therefore suggested that PGE₂ facilitates the development of the gastric SW by an action on the muscle that does not involve cholinergic or adrenergic mechanism.