Role of beta-adrenergic mechanisms during exercise in poorly controlled diabetes.
To examine the beta-adrenergic effects of the catecholamines in poorly controlled diabetes, we have studied insulin-deprived alloxan-diabetic (A-D) dogs during 90 min of moderate exercise (100 m/min, 10-12 degrees) alone (C) or with propranolol (5 micrograms . kg-1 . min-1) (P) or combined P and somatostatin infusion (0.5 microgram . kg-1 . min-1) (P + St). In P, in contrast to C, immunoreactive glucagon (IRG) rose only after 50 min of exercise. However, hepatic glucose production (Ra) rose normally. In P + St, IRG fell 50% below basal, and the Ra response to exercise was abolished. Interestingly, in P and P + St, glucose metabolic clearance rate (MCR) rose by 400% above the inadequate MCR response to exercise in C, despite 30% lower insulin levels. Compared with C, free fatty acids (FFA) and lactate were sharply reduced during P and P + St. Plasma glucose (G) did not change in C, but due to elevated glucose uptake, G fell over 120 mg/dl in P, and due to diminished Ra, G fell 170 mg/dl in P + St. Norepinephrine was similar in all groups. Epinephrine and cortisol were higher in P + St by 90 min of exercise, perhaps as a result of hypoglycemia. In summary, during exercise in poorly controlled A-D dogs, beta-blockade does not appear to affect Ra; beta-blockade leads to diminished mobilization of extrahepatic substrate as evidenced by reduced FFA and lactate levels; beta-blockade increases MCR to levels seen in normal dogs during exercise alone.(ABSTRACT TRUNCATED AT 250 WORDS)
Wasserman
D H
DH
Lickley
H L
HL
Vranic
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M
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology*; D004285:Dogs; D004837:Epinephrine / Q000502:physiology*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005934:Glucagon / Q000502:physiology*; D005947:Glucose / Q000378:metabolism; D007700:Kinetics; D007773:Lactates / Q000097:blood; D019344:Lactic Acid; D008099:Liver / Q000378:metabolism; D008297:Male; D009638:Norepinephrine / Q000502:physiology*; D005082:Physical Exertion; D011433:Propranolol / Q000494:pharmacology; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000502:physiology*; D013004:Somatostatin / Q000494:pharmacology
D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007773:Lactates; D011943:Receptors, Adrenergic, beta; D019344:Lactic Acid; D013004:Somatostatin; D005934:Glucagon; D011433:Propranolol; D005947:Glucose; D009638:Norepinephrine; D004837:Epinephrine