Abstract
The present study determined the vasomotor effects of oxidized low-density lipoprotein (ox-LDL) in human saphenous veins and determined whether decreased availability of l-arginine was responsible for the impaired endothelial function. Human saphenous veins were obtained from white males undergoing coronary bypass surgery. We examined the effects of ox-LDL on ACh-induced endothelium-dependent relaxation, sodium nitroprusside-induced endothelium-independent relaxation and 5-HT-induced contraction. ACh-induced vasorelaxation in the presence of l-arginine and ox-LDL was also examined. In addition, we assessed the endothelial influence on the contractile response to 5-HT. ox-LDL significantly inhibited ACh-induced relaxation but did not affect sodium nitroprusside-induced relaxation. l-Arginine pretreatment did not prevent ox-LDL-induced impairment of the relaxation response to ACh. ox-LDL significantly potentiated 5-HT-induced contraction at concentrations between 3 × 10−6 M and 10−4 M, an effect that was endothelium-dependent. Denudation of endothelium also significantly enhanced the contractile response to 5-HT. These data suggest that ox-LDL impairs ACh-induced endothelium-dependent relaxation and enhances 5-HT-induced endothelium-dependent contraction in human saphenous vein.l-Arginine deficiency is not responsible for the endothelial dysfunction induced by ox-LDL in human saphenous vein.
Footnotes
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Send reprint requests to: Randall L. Tackett, Ph.D., College of Pharmacy, University of Georgia, Athens, GA 30602-2356.
- Abbreviations:
- LDL
- low-density lipoprotein
- ox-LDL
- oxidized low-density lipoprotein
- EDRF
- endothelium-derived relaxing factor
- EDHF
- endothelium-derived hyperpolarizing factor
- 5-HT
- serotonin
- ADMA
- asymmetrical dimethylarginine
- EDCF
- endothelium-derived contracting factor
- Received July 15, 1997.
- Accepted October 14, 1997.
- The American Society for Pharmacology and Experimental Therapeutics
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