Influence of diet and carnitine palmitoyltransferase I inhibition on myosin and sarcoplasmic reticulum.
To examine the role of metabolic signals for ventricular myosin expression and activity of the sarcoplasmic reticulum Ca2+ pump, Wistar rats were treated for 7-8 wk with 5 or 50 mg/kg etomoxir, which inhibits fatty acid utilization. The proportion of myosin V1 was increased (P less than 0.05) with 50 mg/kg etomoxir (75 +/- 5% vs. 62 +/- 6% of control rats), whereas both doses increased the rate of Ca2+ uptake. A carbohydrate-rich fat-free diet or 8% sucrose drinking solutions, however, had no effect on myosin and sarcoplasmic reticulum. When rats were fed diets with an increased content (10 or 20%) of sunflower oil, the calorie intake and myosin V1 increased (56 +/- 8 or 64 +/- 8% vs. 44 +/- 6% of control rats). Isocaloric 10% fat diets of varying fatty acid composition (coconut fat, olive oil, or mackerel oil) also induced a higher calorie intake and increased V1 (64 +/- 6, 60 +/- 9, or 65 +/- 8% for the respective oils vs. 44 +/- 6% of control rats) but did not significantly increase rate of Ca2+ uptake. We concluded that calorie-rich diets changed the myosin expression not by affecting the ratio of fatty acid to glucose utilization but via the increased calorie intake.
Rupp
H
H
Institute of Physiology II, University of Tübingen, Federal Republic of Germany.
Wahl
R
R
Hansen
M
M
D000818:Animals; D001693:Biological Transport, Active; D002118:Calcium / Q000378:metabolism; D050260:Carbohydrate Metabolism; D002334:Carnitine O-Palmitoyltransferase / Q000037:antagonists & inhibitors*; D004032:Diet; D002149:Energy Intake; D004852:Epoxy Compounds / Q000494:pharmacology; D005227:Fatty Acids / Q000378:metabolism; D008297:Male; D009206:Myocardium / Q000378:metabolism; D009218:Myosins / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*
D004852:Epoxy Compounds; D005227:Fatty Acids; D002334:Carnitine O-Palmitoyltransferase; D009218:Myosins; C054207:etomoxir; D002118:Calcium