Hypo- and hyperglycemia in rats: effects on endurance and heat/exercise injury.
To investigate the hypothesis that circulating glucose levels may affect exercise performance and the severity of hyperthermic injury, rats were made hypoglycemic (n = 12, IV insulin, 4 U) or hyperglycemic (n = 12, IP glucose, 750mg) before exercise in the heat to hyperthermic exhaustion (Tco = 42.5-43 degrees C). The endurance of rats administered glucose was significantly greater than insulin-treated controls (n = 12). Hematocrit levels were unaffected by exercise in control and insulin-treated rats, but were significantly (p less than 0.01) increased in those glucose-treated. Lactate levels were increased (p less than 0.001) post-run in all groups, and these increments were exacerebated in glucose-treated rats. Glucose levels pre-run were decreased by insulin and increased by glucose, and remained depressed (p less than 0.01) post-run in the insulin-treated group. Potassium concentrations were reduced (p less than 0.05) by insulin administration. Urea nitrogen and creatinine were increased (p less than 0.001) post-run in all groups. We concluded that, while hyperglycemic rats had increased endurance compared to hypoglycemic animals, mortality of at least 50% in all groups was unaffected by circulating glucose levels.
D000818:Animals; D001786:Blood Glucose / Q000502:physiology*; D001806:Blood Urea Nitrogen; D001831:Body Temperature; D003404:Creatinine / Q000097:blood; D005947:Glucose / Q000494:pharmacology; D006359:Heat Exhaustion / Q000209:etiology*; D006400:Hematocrit; D006943:Hyperglycemia / Q000139:chemically induced; D007003:Hypoglycemia / Q000139:chemically induced; D007328:Insulin; D007773:Lactates / Q000097:blood; D008297:Male; D010807:Physical Endurance; D005082:Physical Exertion; D011188:Potassium / Q000097:blood; D051381:Rats; D012881:Skin Temperature
D001786:Blood Glucose; D007328:Insulin; D007773:Lactates; D003404:Creatinine; D005947:Glucose; D011188:Potassium