Effect of butyrate on membrane potential, ionic currents and intracellular Ca²⁺ concentration in cultured rat myenteric neurones

Abstract

Myenteric neurones from 1–10‐day‐old rats were isolated from the small and large intestine by enzymatic digestion with collagenase. Single cells were collected and kept in culture for up to 1 week. After 1–5 days in culture, membrane potential and ionic currents were measured with the whole‐cell patch‐clamp technique. The intracellular Ca 2+ concentration was measured with the fura‐2 method. The short‐chain fatty acid butyrate (50 mmol L −1 ) induced a reversible hyperpolarization of the myenteric neurones by about 10 mV. This hyperpolarization was concomitant with an inhibition of a TTX‐sensitive Na + current. The hyperpolarization could be suppressed by intracellular application of Cs + , a nonselective K + channel blocker. Fura‐2 experiments revealed that butyrate induced an increase of the intracellular Ca 2+ concentration. The butyrate response was suppressed by thapsigargin, indicating that butyrate stimulates the release of intracellular Ca 2+ . This release is responsible for the voltage response, because intracellular chelation of Ca 2+ inhibited the butyrate induced hyperpolarization. Consequently, butyrate acts on enteric neurones by releasing Ca 2+ from intracellular stores with the consequence of the activation of K + channels, followed by a hyperpolarization.