Changes in blood glucose concentration in the carotid body-sinus modify brain glucose retention.
To test whether blood glucose concentration in the carotid body-sinus may influence the amount of glucose retained by the brain, the isolated carotid sinus was perfused with glucose-rich blood or glucose-poor blood from a second animal. The circulation of the right carotid body-sinus was temporarily isolated in rat A, and perfused with blood coming from rat B. Blood glucose in rat B was modified by injections of glucose or insulin. Changes in glucose retention by the brain were measured in rat A. When the isolated carotid body-sinus in rat A was perfused with hyperglycemic blood (16.7 mM), brain glucose retention in rat A decreased significantly from 0.14 +/- 0.02 mumol/g/min (t = 0) to 0.08 +/- 0.01 mumol/g/min at 4 min after the beginning of perfusion. In contrast, the perfusion of the isolated carotid body-sinus of rat A with hypoglycemic blood (2.7 mM) from rat B, had the opposite effect. Brain glucose retention in rat A increased (0.23 +/- 0.03 mumol/g/min) at t = 4 min in comparison to control values (0.13 +/- 0.01 mumol/g/min). Chemoreceptor activity was also manipulated by the injection of cyanide (NaCN) in rat B, under these conditions, brain glucose retention in rat A increased from 0.13 +/- 0.01 mumol/g/min to 0.28 +/- 0.03 mumol/g/min between 4 to 8 min after the beginning of perfusion. These results indicate that chemosensory activity within the carotid body-sinus, superfused in vivo with different glucose concentrations, modify glucose retention by the brain.
Alvarez-Buylla
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Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Col. México, Mexico.
Roces de Alvarez-Buylla
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D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D001923:Brain Chemistry / Q000502:physiology*; D002344:Carotid Body / Q000166:cytology / Q000378:metabolism*; D002628:Chemoreceptor Cells / Q000187:drug effects; D003486:Cyanides / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism* / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D010101:Oxygen Consumption / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar
D001786:Blood Glucose; D003486:Cyanides; D007328:Insulin; D005947:Glucose