title: Even and carbon dioxide independent distribution of nitrite between plasma and erythrocytes of healthy humans at rest.
abstract: In the literature, the distribution of nitrite and nitrate, the major metabolites of nitric oxide (NO), between plasma and erythrocytes and its dependency on partial CO₂ pressure (pCO₂) in mammalian blood are uncertain. By means of a previously reported fully validated stable-isotope dilution gas chromatography-mass spectrometry (GC-MS) method, we measured nitrite and nitrate concentrations in heparinized plasma from venous, arterial and arterialized blood donated by five healthy non-exercising volunteers at three different time points (0, 15, 30 min). pCO₂, pH and oxygen saturation were measured by standard techniques. The nitrite and nitrate concentrations and the nitrite-to-nitrate ratio in plasma did not correlate with pCO₂ (r=-0.272, P=0.07). Nitrite was found to be almost evenly distributed between plasma and erythrocytes of another eleven healthy non-exercising subjects. In a rabbit model of ARDS, no differences were found in the plasma nitrite and nitrate concentrations comparing normoventilation with hypercapnia. Our studies suggest that the distribution of nitrite between plasma and erythrocytes at rest is largely even and independent of pCO₂ in blood of healthy humans and rabbits with ARDS.
authors.affiliation: Institute of Clinical Pharmacology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany. tsikas.dimitros@mh-hannover.de
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Tsikas
authors.forename: Karina
authors.initials: K
authors.lastname: Sutmöller
authors.forename: Mirja
authors.initials: M
authors.lastname: Maassen
authors.forename: Marisa
authors.initials: M
authors.lastname: Nacke
authors.forename: Anke
authors.initials: A
authors.lastname: Böhmer
authors.forename: Anja
authors.initials: A
authors.lastname: Mitschke
authors.forename: Hannelore
authors.initials: H
authors.lastname: Konrad
authors.forename: Henning
authors.initials: H
authors.lastname: Starke
authors.forename: Helmut
authors.initials: H
authors.lastname: Hummler
authors.forename: Norbert
authors.initials: N
authors.lastname: Maassen
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D000818:Animals; D002245:Carbon Dioxide / Q000097:blood*; D004912:Erythrocytes / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009573:Nitrites / Q000097:blood*; D011817:Rabbits; D012146:Rest / Q000502:physiology*
chemical_list: D009573:Nitrites; D002245:Carbon Dioxide