Diabetic rat hearts exhibited significantly greater triacylglycerol turnover rates compared to normal hearts under high-substrate conditions (820 vs 190 nmol/min/g dry wt; P<0.001).
Diabetic rat hearts exhibit accelerated triacylglycerol turnover and evidence of compartmentalized lipid storage compared to normal hearts.
Absolute Event Rate: 820% vs 190%
p-value: p=<0.001
Triacylglycerol (TAG) storage and turnover rates in the intact, beating rat heart were determined for the first time using dynamic mode (13)C- NMR spectroscopy to elucidate profound differences between hearts from diabetic rats (DR, streptozotocin treatment) and normal rats (NR). The incorporation of 2,4,6,8,10,12,14,16-(13)C(8)palmitate into the TAG pool was monitored in isolated hearts perfused with physiological (0.5 mM palmitate, 5 mM glucose) and elevated substrate levels (1.2 mM palmitate, 11 mM glucose) characteristic of the diabetic condition. Surprisingly, although the normal hearts were enriched at a near-linear profile for >or=2 h before exponential characterization, exponential enrichment of TAG in diabetic hearts reached steady state after only 45 min. Consequently, TAG turnover rate was determined by fitting an exponential model to enrichment data rather than conventional two-point linear analysis. In the high-substrate group, both turnover rate (DR 820+/- 330, NR 190 +/-150 nmol.min(-1).g(-1) dry wt; P< 0.001) and TAG content (DR 78 +/-10, NR 32+/- 4 micromol/g dry wt; P< 0.001) were greater in the diabetic group. At lower substrate concentrations, turnover was greater in diabetics (DR 530+/-300, NR 160+/- 30; P<0.05). However, this could not be explained by simple mass action, because TAG content was similar between groups DR 34+/- 7, NR 39+/- 9 micromol/g dry wt; not significant (NS). Consistent with exponential enrichment data, (13)C fractional enrichment of TAG was lower in diabetics (low- substrate groups: DR 4+/-1%, NR 10+/- 4%, P<0.05; high-substrate groups: DR 8+/- 3%, NR 14+/- 9%, NS), thereby supporting earlier speculation that TAG is compartmentalized in the diabetic heart.
O’Donnell et al. (Wed,) conducted a other in Diabetes. Diabetic condition (streptozotocin treatment) vs. Normal rats was evaluated on Triacylglycerol (TAG) turnover rate in high-substrate group (nmol.min(-1).g(-1) dry wt) (p=<0.001). Diabetic rat hearts exhibited significantly greater triacylglycerol turnover rates compared to normal hearts under high-substrate conditions (820 vs 190 nmol/min/g dry wt; P<0.001).