Effects of subbasal insulin infusion on resting and exercise-induced glucose turnover in depancreatized dogs.
beta-Adrenergic blockade suppressed lipolysis and normalized the exercise-induced increments in glucose uptake (GlcU) and metabolic clearance rate (MCR) in alloxan-diabetic dogs with residual insulin, but not in insulin-deprived depancreatized dogs even when combined with methylpalmoxirate (MP), which suppresses fatty acid oxidation. The effects of a minimal amount of insulin (as in the alloxan-diabetic dog), were studied in depancreatized, 24-h insulin-deprived dogs during rest and treadmill exercise (6 km/h, 10% slope) using a 1/4 basal insulin infusion (50 microU.kg-1.min-1, insulin, n = 6) alone, or with MP (20 mg.kg-1.day orally, 2.5 days, MP+insulin, n = 6). At rest, insulin decreased circulating fatty acids (31%) and Glc (13%) and increased GlcU and MCR (86 and 72%). Glc production was unaffected. MP plus insulin markedly suppressed hepatic fatty acid oxidation, decreased Glc (44%) and Glc production (50%), and markedly increased MCR (128%). The exercise-induced increments in MCR were markedly improved only by MP plus insulin but were still lower than in the propranolol-treated alloxan-diabetic dogs. Plasma Glc inversely correlated with the exercise-induced increase in MCR (r = -0.86). We conclude that 1) acute infusion of subbasal insulin improved GlcU in depancreatized dogs at rest but not during exercise; 2) inhibition of fatty acid oxidation combined with subbasal insulin improved the exercise-induced increase in MCR; and 3) the difference in GlcU and MCR between the MP plus insulin-treated depancreatized dogs and the beta-blockade-treated alloxan-diabetic dogs suggests a difference between acute and chronic effects of insulin.
Shi
Z Q
ZQ
Department of Physiology, University of Toronto, Ontario, Canada.
Giacca
A
A
Yamatani
K
K
Fisher
S J
SJ
Lickley
H L
HL
Vranic
M
M
D020155:3-Hydroxybutyric Acid; D000496:Alloxan; D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000378:metabolism; D004285:Dogs; D004852:Epoxy Compounds / Q000494:pharmacology; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005947:Glucose / Q000378:metabolism*; D006885:Hydroxybutyrates / Q000097:blood; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007262:Infusions, Intravenous; D007328:Insulin / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D008297:Male; D008657:Metabolic Clearance Rate; D010179:Pancreas / Q000502:physiology; D010180:Pancreatectomy; D010805:Physical Conditioning, Animal; D011422:Propionates / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D012146:Rest / Q000502:physiology*; D013997:Time Factors
D004852:Epoxy Compounds; D005230:Fatty Acids, Nonesterified; D006885:Hydroxybutyrates; D007004:Hypoglycemic Agents; D007328:Insulin; D011422:Propionates; D000496:Alloxan; D011433:Propranolol; D005947:Glucose; C017522:methyl 2-tetradecylglycidate; D020155:3-Hydroxybutyric Acid