Mechanisms of Low-Glucose Sensitivity in Carotid Body

Carotid body activation by hypoglycemia Objective: Glucose sensing is essential for the adaptive counterregulatory responses to hypoglycemia. We investigated the mechanisms underlying carotid body (CB) glomus cells activation by low glucose. Research Design and Methods and Results: Removal of extracellular glucose elicited a cell secretory response, abolished by blockade of plasma membrane Ca2+ channels, and a reversible increase in cytosolic Ca2+ concentration. These data indicated that glucopenia induces transmembrane Ca2+ influx and transmitter secretion. In patch clamped glomus cells exposure to low glucose resulted in inhibition of macroscopic outward K+ currents and in the generation of a depolarizing receptor potential (DRP). The DRP was abolished upon removal of extracellular Na+. The membrane-permeable 1-oleoyl-2-acetyl-sn-glycerol induced inward currents of similar characteristics as the current triggered by glucose deficiency. The functional and pharmacological analyses suggest that low glucose activates background cationic Na+