title: The Effects of Blood Glucose Concentration on the Shivering Threshold in Rabbits.
abstract: BACKGROUND
  Hyperglycemia is common in critically ill and surgical patients, as are core temperature disturbances. The effect of hyperglycemia on thermoregulatory defenses remains unknown. We determined the effect of blood glucose concentration on the shivering threshold in rabbits.
  
  
  METHODS
  Twenty-seven rabbits lightly anesthetized with isoflurane were randomly assigned to infusions of (1) saline, (2) insulin titrated to produce blood glucose concentrations 60 to 100 mg/dL, or (3) 50% dextrose titrated to produce blood glucose concentrations 200 to 300 mg/dL. Core temperature was reduced at a rate of 2 to 3°C/h by perfusing water at 10°C through a plastic tube positioned in the colon. Cooling continued until shivering was observed by an investigator blinded to treatment or until esophageal (core) temperature reached 34°C. Core temperatures at the onset of shivering defined the threshold. All analyses were conducted using SAS version 9.3 (SAS Institute Inc., Cary, NC).
  
  
  RESULTS
  Rabbits given saline shivered at 37.2 ± 0.5°C (mean ± SD). Rabbits given insulin shivered at 36.3 ± 1.1°C. Rabbits given dextrose shivered at 38.0 ± 0.6°C. The shivering threshold increased as a function of blood glucose concentration: shivering threshold (°C) = 0.009 [blood glucose concentration (mg/dL)] + 35.6, r = 0.53. The shivering threshold thus increased approximately 1°C for each 100 mg/dL increase in blood glucose concentration.
  
  
  CONCLUSIONS
  Hyperglycemia increases the threshold for shivering, whereas hypoglycemia lowers the threshold on rabbits.
authors.affiliation: From the *Department of Anesthesiology, University of Yamanashi, Tokyo, Japan; †Department of Anesthesiology, Shizuoka Children's Hospital, Tokyo, Japan; ‡Department of Anesthesiology, Fujiyoshida Municipal Hospital, Tokyo, Japan; and §Department of Outcomes Research, Cleveland Clinic, Cleveland, Ohio.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Ino
authors.forename: Taishi
authors.initials: T
authors.lastname: Masamune
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Sato
authors.forename: Katsumi
authors.initials: K
authors.lastname: Okuyama
authors.forename: Keiichi
authors.initials: K
authors.lastname: Wada
authors.forename: Hironobu
authors.initials: H
authors.lastname: Iwashita
authors.forename: Tadahiko
authors.initials: T
authors.lastname: Ishiyama
authors.forename: Takeshi
authors.initials: T
authors.lastname: Oguchi
authors.forename: Daniel I
authors.initials: DI
authors.lastname: Sessler
authors.forename: Takashi
authors.initials: T
authors.lastname: Matsukawa
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism*; D004195:Disease Models, Animal; D005947:Glucose; D006943:Hyperglycemia / Q000097:blood* / Q000139:chemically induced / Q000503:physiopathology*; D007003:Hypoglycemia / Q000097:blood* / Q000139:chemically induced / Q000503:physiopathology; D007328:Insulin; D008297:Male; D011817:Rabbits; D012684:Sensory Thresholds / Q000187:drug effects; D012768:Shivering / Q000187:drug effects; D013997:Time Factors
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D007328:Insulin; D005947:Glucose