Involvement of adenosine triphosphate-sensitive K+ channels in glucose-sensing in the rat solitary tract nucleus

The presence of adenosine triphosphate-sensitive (ATP-sensitive) K+ channels (K(ATP) channels) in the caudal nucleus tractus solitarii (NTS), and their possible involvement in glucose-sensing, were assessed by extracellular recording of neuronal activity in rat hindbrain slices. In 21 out of 36 recorded cells, firing was increased by sulfonylureas and decreased by K+ channel opener (KCO), indicating the existence of K(ATP) channels in the caudal NTS. In seven out of the nine neurons activated by a 2 mM increase in the glucose level, the effects of sulfonylureas and KCO were consistent with the involvement of K(ATP) channels in the glucose response. Conversely, the mechanism(s) underlying the response of glucose-depressed neurons remains to be clarified. Finally, the presence of K(ATP) channels was also detected in some neurons that were unresponsive to a 2 mM change in the glucose level. Thus, K(ATP) channels were pharmacologically identified in the caudal NTS, where they may be partly involved in glucose sensing.