NO synthesis, unlike respiration, influences intracellular oxygen tension.
We have developed a new phosphorescent probe, PdTCPPNa(4), whose luminescence properties are affected by local variations of intracellular oxygen tension (PO(2)). Spectrofluorometric measurements on living human umbilical venous endothelial cells loaded with this molecule show that a decrease in extracellular oxygen tension induces a decrease of PO(2), illustrating the phenomenon of oxygen diffusion and validating the use of this probe in living cells. Moreover, KCN- or 2,4-dinitrophenol-induced modifications of respiration do not lead to detectable PO(2) variations, probably because O(2) diffusion is sufficient to allow oxygen supply. On the contrary, activation by acetylcholine or endothelial nitric oxide synthase (eNOS), which produces NO while consuming oxygen, induces a significant decrease in PO(2), whose amplitude is dependent on the acetylcholine dose, i.e., the eNOS activity level. Hence, activated cytosolic enzymes could consume high levels of oxygen which cannot be supplied by diffusion, leading to PO(2) decrease. Other cell physiology mechanisms leading to PO(2) variations can now be studied in living cells with this probe.
Coste
Jerome
J
Groupe d'Electrophysiologie Moléculaire, Université J. Fourier, BP 53X, 38041 Grenoble, France.
Vial
Jean-Claude
JC
Faury
Gilles
G
Deronzier
Alain
A
Usson
Yves
Y
Robert-Nicoud
Michel
M
Verdetti
Jean
J
D019297:2,4-Dinitrophenol / Q000494:pharmacology; D000109:Acetylcholine / Q000378:metabolism / Q000494:pharmacology; D002478:Cells, Cultured; D003593:Cytoplasm / Q000201:enzymology; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000166:cytology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III; D010100:Oxygen / Q000378:metabolism*; D011166:Porphyrins / Q000378:metabolism; D011190:Potassium Cyanide / Q000494:pharmacology; D011312:Pressure; D013050:Spectrometry, Fluorescence; D013997:Time Factors; D014471:Umbilical Veins / Q000166:cytology; D014475:Uncoupling Agents / Q000494:pharmacology
D004791:Enzyme Inhibitors; D011166:Porphyrins; D014475:Uncoupling Agents; D009569:Nitric Oxide; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; D011190:Potassium Cyanide; D000109:Acetylcholine; D019297:2,4-Dinitrophenol; D010100:Oxygen