Utilisation of triacylglycerol and non-esterified fatty acid by the working rat heart: myocardial lipid substrate preference.
Utilisation and subsequent metabolic fate (oxidation; tissue lipid deposition) of non-esterified fatty acid (NEFA), very-low-density lipoprotein-triacylglycerol (VLDL-TAG), and chylomicron-triacylglycerol (CM-TAG) alone or in combination by isolated working rat heart were examined. Cardiac mechanical function was maintained regardless of lipid substrate used. NEFA and CM-TAG were assimilated to a greater extent than VLDL-TAG; CM-TAG utilisation (76+/-10 nmol fatty acid/min per g wet wt.; n=8), but not VLDL-TAG utilisation (16+/-2 nmol fatty acid/min per g wet wt.; n=8), was suppressed in the presence of NEFA, but TAG (CM or VLDL) did not alter NEFA utilisation (57+/-9 nmol fatty acid/min per g wet wt.; n=8). Most (about 75%) of the lipid utilised was oxidised. In the presence of NEFA, CM-TAG deposition as tissue lipid was preserved, despite decreased CM-TAG oxidation; metabolic fate of VLDL-TAG was unaffected by NEFA. TAG (CM or VLDL) in the perfusate tended to decrease lipoprotein lipase (LPL) activity; this may be a reflection of increased LPL turnover in the presence of lipoproteins.
Hauton
D
D
Nuffield Department of Anaesthetics, University of Oxford, Radcliffe Infirmary, Woodstock Road, OX2 6HE, Oxford, UK.
Bennett
M J
MJ
Evans
R D
RD
D000818:Animals; D002250:Carbon Radioisotopes; D002914:Chylomicrons / Q000378:metabolism; D004734:Energy Metabolism; D005230:Fatty Acids, Nonesterified / Q000378:metabolism*; D006321:Heart / Q000502:physiology*; D008071:Lipoprotein Lipase / Q000378:metabolism; D008079:Lipoproteins, VLDL / Q000378:metabolism; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D010477:Perfusion; D051381:Rats; D017208:Rats, Wistar; D014280:Triglycerides / Q000378:metabolism*; D014304:Triolein / Q000378:metabolism; D014316:Tritium
D002250:Carbon Radioisotopes; D002914:Chylomicrons; D005230:Fatty Acids, Nonesterified; D008079:Lipoproteins, VLDL; D014280:Triglycerides; C030106:very low density lipoprotein triglyceride; D014316:Tritium; D014304:Triolein; D008071:Lipoprotein Lipase