Effect of hypoxia and hypoxia/reoxygenation on proteoglycan metabolism by vascular smooth muscle cells.
Hypoxia and hypoxia/reoxygenation are known to affect vascular smooth muscle cell physiology. In this study, we first investigated proteoglycan synthesis by human aortic smooth muscle cells exposed to normoxia, hypoxia, or hypoxia/reoxygenation. We then compared the newly synthesized proteoglycans from normoxic and hypoxic-reoxygenation cultures for their ability to bind low density lipoprotein (LDL). Confluent smooth muscle cells under normoxia, hypoxia, or hypoxia/reoxygenation were pulsed with [35S]sulfate, and secreted and cell-associated proteoglycans were analyzed. Secreted proteoglycans in cultures exposed to hypoxia (4 h)/reoxygenation (19 h) increased 28% over those of cells continuously exposed to normoxia. Cell-associated proteoglycans did not differ significantly between the two groups. In contrast, hypoxia (4 h) followed by a 30-min reoxygenation produced a 37% decrease in newly synthesized proteoglycans. Hypoxia alone also resulted in a 24% decrease in secreted proteoglycans and a 20% decrease in cell-associated proteoglycans. Proteoglycans newly synthesized by smooth muscle cells exposed to normoxia and hypoxia/reoxygenation did not differ in their charge densities and molecular size but did differ in glycosaminoglycan composition. Exposure of smooth muscle cells to hypoxia/reoxygenation produced a 60% increase in a proteoglycan subfraction that bound LDL with very high affinity. The incorporation of [3H]leucine into total cellular protein decreased significantly following exposure of smooth muscle cells to hypoxia as well as hypoxia/reoxygenation. These results indicate that hypoxia and hypoxia/reoxygenation cause major alterations in proteoglycan metabolism by vascular smooth muscle cells.
Figueroa
J E
JE
Section of Infectious Diseases, Louisiana State University Medical Center, New Orleans 70112, USA.
Tao
Z
Z
Sarphie
T G
TG
Smart
F W
FW
Glancy
D L
DL
Vijayagopal
P
P
D001011:Aorta; D015687:Cell Hypoxia; D002478:Cells, Cultured; D006801:Humans; D008077:Lipoproteins, LDL / Q000378:metabolism; D008855:Microscopy, Electron, Scanning; D009131:Muscle, Smooth, Vascular / Q000378:metabolism* / Q000648:ultrastructure; D010100:Oxygen / Q000502:physiology*; D014176:Protein Biosynthesis; D011509:Proteoglycans / Q000096:biosynthesis* / Q000378:metabolism
D008077:Lipoproteins, LDL; D011509:Proteoglycans; D010100:Oxygen