Ascorbate uptake in pig coronary artery endothelial cells.
Although smooth muscle and endothelial cells in pig coronary artery are morphologically and functionally distinct, ascorbate uptake has been characterized only in smooth muscle cells. Ascorbate transporters in kidney and intestinal epithelial cells differ from those in smooth muscle. We examined ascorbate transport and mRNA expression of sodium-dependent vitamin C transporters (SVCT) by RT-PCR in the pig coronary artery endothelial cell cultures. When 14C-ascorbate uptake in endothelial cells was examined as 14C or by HPLC, the two values did not differ from each other. 14C-ascorbate uptake was Na(+)-dependent, stereoselective for L-ascorbate and inhibited by sulfinpyrazone. The kinetic characteristics of the uptake were: Km = 27 +/- 3 microM (Hill coefficient = 1) for ascorbate and Km = 73 +/- 14 mM (Hill coefficient = 2) for Na+. Surprisingly, endothelial cells had similar kinetic parameters as smooth muscle cells, except for a slightly lower uptake velocity in endothelial cells. Comparison with the smooth muscle showed that both tissue types expressed mRNA for SVCT2. Endothelial cells differ from epithelial cells which express mainly SVCT1 but resemble smooth muscle cells in this respect.
Best
Kelly A
KA
Department of Biology, McMaster University, Hamilton Ontario, Canada.
Holmes
Melanie E
ME
Samson
Sue E
SE
Mwanjewe
James
J
Wilson
John X
JX
Dixon
S Jeffrey
SJ
Grover
Ashok K
AK
D000818:Animals; D001205:Ascorbic Acid / Q000493:pharmacokinetics*; D001692:Biological Transport / Q000187:drug effects; D002478:Cells, Cultured; D003331:Coronary Vessels / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D003683:Dehydroascorbic Acid / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism; D008969:Molecular Sequence Data; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism; D029363:Organic Anion Transporters, Sodium-Dependent / Q000235:genetics / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D060347:Sodium-Coupled Vitamin C Transporters; D013442:Sulfinpyrazone / Q000494:pharmacology; D013552:Swine; D027981:Symporters / Q000235:genetics / Q000378:metabolism; D013997:Time Factors
D029363:Organic Anion Transporters, Sodium-Dependent; D060347:Sodium-Coupled Vitamin C Transporters; D027981:Symporters; D012964:Sodium; D001205:Ascorbic Acid; D013442:Sulfinpyrazone; D003683:Dehydroascorbic Acid