Simultaneous measurement of NO(*) and PO(2) from tissue by in vivo EPR.
We describe a technique that utilizes electron paramagnetic resonance (EPR) to measure NO(*) and pO(2) directly, and non-invasively, from tissue in vivo. Diethyldithiocarbamate (DETC) was injected with iron so as to complex with NO(*) in the tissue. Gloxy (an oxygen-sensitive, paramagnetic material) was also implanted into the tissue of interest (brain or liver). Because the signals arising from gloxy and NO-Fe-(DETC)(2) did not overlap, they could be monitored and measured simultaneously in vivo. The gloxy was not responsive to NO(*) and/or DETC. As model systems we either injected SNP (an NO(*) donor) into animals and monitored NO(*) and pO(2) simultaneously from brain, or endotoxin (lipopolysaccharide; LPS) was injected in order to induce a septic episode and NO(*) and pO(2) measured from liver. We found a close correlation between levels of SNP-derived NO(*) and brain pO(2) in vivo. During sepsis, liver pO(2) decreased dramatically at 300-360 min after endotoxin injection, and this coincided with decreases in mean arterial blood pressure and increased tissue NO(*) detected. These studies demonstrate the potential usefulness of this technique for making direct in vivo measurements of NO(*) and pO(2) simultaneously from tissue.
James
P E
PE
Department of Radiology, Dartmouth Medical School, Hanover, New Hampshire, USA. Jamespp@cardiff.ac.uk
Miyake
M
M
Swartz
H M
HM
D000818:Animals; D001923:Brain Chemistry; D002244:Carbon / Q000737:chemistry; D015687:Cell Hypoxia; D004050:Ditiocarb / Q000031:analogs & derivatives; D004578:Electron Spin Resonance Spectroscopy; D019446:Endotoxemia / Q000378:metabolism; D005296:Ferrous Compounds; D008099:Liver / Q000737:chemistry*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009569:Nitric Oxide / Q000032:analysis*; D020030:Nitric Oxide Donors; D009599:Nitroprusside; D009928:Organ Specificity; D010100:Oxygen / Q000032:analysis*; D010313:Partial Pressure; D014664:Vasodilation
D005296:Ferrous Compounds; D020030:Nitric Oxide Donors; C085124:diethyldithiocarbamate iron(II); D009599:Nitroprusside; D009569:Nitric Oxide; D002244:Carbon; D004050:Ditiocarb; D010100:Oxygen