The nitric oxide pathway is amplified in venular vs arteriolar cultured rat mesenteric endothelial cells.
To determine if there are differences in nitric oxide activity between pre- and postcapillary microvessels, we studied cultured rat mesenteric arteriolar and venular endothelial cells (RMAEC, RMVEC). We measured expression of endothelial nitric oxide synthase (eNOS), the activity of eNOS, and L-arginine transport in live RMAEC and RMVEC and the L-arginine content of RMAEC and RMVEC lysates. The abundance of eNOS was significantly greater in RMVEC vs RMAEC; this was also true for freshly harvested, pooled microvessels. Baseline NOS activity was higher in RMVEC than in RMAEC. NG-monomethyl-L-arginine (L-NMA; 5 mM) inhibited NOS activity by approximately 70-80% in both RMAEC and RMVEC, indicating that metabolism of l-arginine is largely via NOS. Intracellular L-arginine levels were higher in RMVEC vs RMAEC and well above the eNOS Km in both cell types. L-arginine levels increased with L-NMA in both RMAEC and RMVEC, presumably due to reduced substrate utilization. Since L-arginine transport was not higher in RMVEC vs RMAEC, this may reflect higher intracellular arginine synthesis. A higher intrinsic level of baseline NO production in the postcapillary microvascular endothelium may reflect both the contribution of venular derived NO to control of arteriolar tone and a key role of venular-derived NO in local thrombosis control.
Wagner
L
L
Department of Physiology, West Virginia University, Morgantown, West Virginia 26506, USA.
Hoey
J G
JG
Erdely
A
A
Boegehold
M A
MA
Baylis
C
C
D000818:Animals; D001120:Arginine / Q000378:metabolism; D001160:Arterioles / Q000166:cytology / Q000378:metabolism*; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D015153:Blotting, Western; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III; D051381:Rats; D017207:Rats, Sprague-Dawley; D013152:Splanchnic Circulation; D014699:Venules / Q000166:cytology / Q000378:metabolism*; D019323:omega-N-Methylarginine / Q000494:pharmacology
D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D001120:Arginine; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat