Aortic enzymes and lactate in high altitude-raised and cholesterol-fed rabbits

Favourable modulation of the inflammatory changes in hypercholesterolemic atherogenesis by a low-molecular-weight heparin derivative

BACKGROUND

In the hypercholesterolemic state, the net result of combined oxidative and nitrosative stress is a pro-inflammatory phenotype that is manifested as increased adhesion molecule expression, enhanced leucocyte trafficking, and increased vascular permeability. The present work explores the inflammatory aspects of hypercholesterolemic atherogenesis, and also evaluates the role of a low-molecular-weight heparin derivative (LMWH), Certoparin, on a biochemical basis.

METHODS AND RESULTS

Two groups of male Wistar rats were fed an atherogenic diet (normal rat chow plus 4% cholesterol, 1% cholic acid and 0.5% thiouracil-CCT diet) for 2 weeks. While one was left untreated, the other was administered LMWH (300 microg/day/rat commencing on day 8 and continued for a week). Increased concentrations of plasma C-reactive protein and fibrinogen and cardiac TNF-alpha indicated severe inflammation in the atherogenic diet fed rats. In comparison, these biochemical indices of inflammation diminished significantly in the LMWH treated group (p < 0.001). Significant depletion of thiols, along with accentuated activities of the glutathione metabolising was observed in the cardiac and hepatic tissues of the untreated atherogenic rats, indicating heightened oxidative response. Tissue damage was marked by elevated levels of plasma and tissue hexose, hexosamine, hexuronic acid and sialic acid, which were reversed towards normalcy on LMWH administration. The activities of lysosomal enzymes (N-acetyl glucosaminidase, beta-glucuronidase, beta-galactosaminidase and cathepsin-D) showed a marked increase in the CCT-diet fed rats, while LMWH treated rats showed normal activities (p < 0.001). The osmotic fragility test revealed that the untreated hyperlipidemic rat erythrocytes were significantly fragile at high salt concentrations, while the response was normalized in the LMWH treated group (p < 0.05). Further, hypercholesterolemia induced downregulation of physiological nitric oxide levels was corrected upon treatment with heparin-derivative.

CONCLUSION

The results of this work highlight the inflammatory changes in atherogenic conditions and that the low-molecular-weight heparin derivative affords substantial protection.

Effects of human low-density lipoproteins on the nucleotide patterns of cultured pig aortic endothelial cells

Cultured pig aortic endothelial cells display significant changes in their nucleotide patterns after incubation with LDL-cholesterol purified from normal human plasma as determined by HPLC. Incubation at 70 mg/dl LDL-cholesterol for 24 h at 37 degrees C caused a significant decrease (P less than 0.001) in ATP from a control value of 14.0 +/- 0.4 nmol/mg protein to 6.6 +/- 0.9 nmol/mg protein (n = 4) with a concomitant increase in ADP and AMP. At higher LDL concentrations these effects were even more pronounced but still reversible. Akin to adenine nucleotides, the guanosine and uridine phosphates as determined by HPLC were changed. In contrast to LDL, HDL and VLDL were ineffectual.