Glycolytic ATP production regulates muscarinic cation currents in guinea-pig ileum.

We investigated the possible sources of intracellular ATP which was previously shown essential for maintaining the muscarinic cationic channel activities (or currents; I(cat)) in guinea-pig ileal myocytes, using two variants of patch clamp techniques. Deprivation of external glucose or its replacement with 2-deoxyglucose significantly reduced the magnitude of I(cat), recorded with nystatin-perforated method, with greater efficacy than for voltage-dependent Ca2+ current Intracellular dialysis of ileal myocytes with key substrates for glycolysis, oxidative metabolism and creatine-phosphocreatine system all resulted in a comparably effective maintenance of I(cat), which was abolished by inhibitors for these ATP-producing systems, 3-bromopyruvate, cyanide and 2,4-dinitrofluorobenzene (DNFB), respectively. However, amongst these inhibitors, only 3-bromopyruvate effectively reduced I(cat) recorded with the nystatin-perforated method. These results strongly suggest the exclusive physiological importance of glycolytic ATP production in maintaining I(cat), activity, and thus this mechanism may play a role in the regulation of gut motility.