Characterization of 5‐hydroxytryptamine receptors mediating mucosal secretion in guinea‐pig ileum

Abstract

The receptor subtypes through which 5‐hydroxytryptamine (5‐HT) increases electrolyte secretion across the mucosa of guinea‐pig ileum were studied. Flat sheep preparations of guinea‐pig mucosa plus submucosa were placed in Ussing chambers and the short circuit current (ISC), an index of net electrogenic electrolyte transport across the mucosa, was measured under voltage clamp conditions. Low concentrations of 5‐HT (10–300 nm) evoked monophasic increases in ISC which were significantly reduced by hyoscine (100 nm), tetrodotoxin (TTX, 300 nm) and the 5‐HT2 receptor antagonist, ketanserin (3–300 nm). Higher concentrations of 5‐HT (1–10 μm) produced biphasic responses which were reduced by hyosci..