Significant blood resistance to nitric oxide transfer in the lung

Colin D R Borland, Helen Dunningham, Fiona Bottrill, Alain Vuylsteke, Cuneyt Yilmaz, D. Merril Dane, Connie C W Hsia

Research output: Contribution to journalArticlepeer-review

53 Scopus citations

Abstract

Lung diffusing capacity for nitric oxide (DLNO) is used to measure alveolar membrane conductance (DMNO), but disagreement remains as to whether DMNO= DLNO, and whether blood conductance (θNO) = ∞. Our previous in vitro and in vivo studies suggested that θNO < ∞. We now show in a membrane oxygenator model perfused with whole blood that addition of a cell-free bovine hemoglobin (Hb) glutamer-200 solution increased diffusing capacity of the circuit (D) for NO (DNO) by 39%, D for carbon monoxide (Dco) by 24%, and the ratio of DLNO to Dco by 12% (all P < 0.001). In three anesthetized dogs, DLNO and DLCO were measured by a rebreathing technique before and after three successive equal volume-exchange transfusions with bovine Hb glutamer-200 (10 ml/kg each, total exchange 30 ml/kg). At baseline, DLNO/DLCO= 4.5. After exchange transfusion, DLNO rose 57 ± 16% (mean ± SD, P = 0.02) and DLNO/DLCO = 7.1, whereas DLCO remained unchanged. Thus, in vitro and in vivo data directly demonstrate a finite θNO. We conclude that the erythrocyte and/or its immediate environment imposes considerable resistance to alveolar-capillary NO uptake. DLNO is sensitive to dynamic hematological factors and is not a pure index of conductance of the alveolar tissue membrane. With successive exchange transfusion, the estimated in vivo θNO [5.1 ml NO·(ml blood·min·Torr)-1] approached 4.5 ml NO·(ml blood·min·Torr)-1, which was derived from in vitro measurements by Carlsen and Comroe (J Gen Physiol 42: 83-107, 1958). Therefore, we suggest use of θNo = 4.5 ml NO·(min· Torr·ml blood)-1 for calculation of DMNO and pulmonary capillary blood volume from DLNO and DLCO

Original languageEnglish (US)
Pages (from-to)1052-1060
Number of pages9
JournalJournal of applied physiology
Volume108
Issue number5
DOIs
StatePublished - May 2010

Keywords

  • Blood substitute
  • Bovine hemoglobin glutamer
  • Carbon monoxide
  • Exchange transfusion
  • Gas exchange
  • Lung diffusing capacity
  • Lung diffusing capacity for carbon monoxide
  • Lung diffusing capacity for nitric oxide
  • Membrane diffusing capacity
  • Membrane oxygenator

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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