Effect of sucrose diet on insulin secretion in vivo and in vitro and on triglyceride storage and mobilisation of the heart of rats.
Basal heart triacylglycerol (TG) (mumole triacylglycerol/g of dry weight) (- before "in vitro" Langendorff perfusion -) was significantly higher in animals rendered chronically hypertriglyceridaemic (H) by a 63% sucrose-rich diet than in controls (C, standard diet); 28 +/- 2.6 means + SEM vs. 19.3 +/- 1.2; respectively (p less than 0.01). After 40' perfusion with Krebs-Henseleit buffer + 5.5 mM glucose, 2.5 mM Ca++, TG content fell to 14.2 +/- 0.6 in C and 14.9 +/- 1.9 in H (n.S.). Administration of 1 n mol x min-1 of glucagon (Gn) from min 20 to 40 reduced TG to 9.0 +/- 0.5 in C (p less than 0.05). In contrast no effect of Gn was observed in H (TG at min 40: 16.7 +/- 2.5). Glycogen (Gly) content (mumol/g of dry weight) after Gn perfusion fell from 30 +/- 1.9 to 17 +/- 2.1 (p less than 0.01) in C, while again no effect was recorded in H. "In vivo" plasma glucose fractional coefficient disappearance rate was lower (p less than 0.001) in H: 1.01 x 10(-2) +/- 0.09 x 10(-2) vs 2.61 x 10(-2) +/- 0.14 x 10(-2) in C, in spite of H showing hyperinsulin secretion. Hyperinsulinism was further documented by "in vitro" Iri release studies from incubated pancreas pieces. In the absence of glucose (G) from the incubation medium H produced 541 +/- 19.8 mU/mg weight Tissue/20', while C produced 91.2 +/- 12.7 (p less than 0.001). With 100 mg% G, H released 1058 +/- 259 and C 377 +/- 82.5 (p less than 0.001). It is suggested that hyperinsulin secretion plus insulin resistance may account for the above findings.
D000818:Animals; D004040:Dietary Carbohydrates / Q000494:pharmacology*; D005934:Glucagon / Q000494:pharmacology; D005951:Glucose Tolerance Test; D006003:Glycogen / Q000032:analysis; D006321:Heart / Q000187:drug effects; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D008053:Lipid Mobilization / Q000187:drug effects*; D008066:Lipolysis / Q000187:drug effects; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013395:Sucrose / Q000494:pharmacology*; D014280:Triglycerides / Q000378:metabolism*
D004040:Dietary Carbohydrates; D007328:Insulin; D014280:Triglycerides; D013395:Sucrose; D006003:Glycogen; D005934:Glucagon