Glucose Sensing Cells in the Carotid Body
As neurons utilize almost exclusively glucose as energy source, brain function depends critically on a steady glucose supply (Martin et al., 1994; Auer et al., 1998). Acute hypoglycemia is counterbalanced by sympathetic activation to increase glucose delivery to blood (Cryer et al., 1981; Cane et al., 1986; Gerich and Campbell, 1988). This homeostatic response is essential for life and particularly important for insulin-treated diabetics, however the underlying mechanisms and site(s) of peripheral blood glucose control remain unknown (Cane et al., 1986; Amiel et al., 1987; Hoffman et al., 1999). Although the existence of glucose-sensitive neurons in the hypothalamus and other areas of the brain is well documented (Biggers et al., 1989; Routh, 2002), there is considerable evidence supporting the existence of peripheral glucose sensors, which are necessary for the proper counterregulatory responses to hypoglycemia. Systemic glucoreceptors have been proposed to exist at the liver, pancreas, portal vein, and carotid bodies (Alvarez-Buylla and Alvarez Buylla, 1988; Donovan et al., 1991; Hevener et al., 2000; Koyama et al., 2000, 2001), nevertheless the physiological role of these glucose sensitive regions is controversial and the glucose sensing cells have not been identified.
KeywordsCarotid Body Secretory Response Glomus Cell Acute Hypoglycemia Sympathoadrenal Response
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