title: The blood transfer conductance for nitric oxide: Infinite vs. finite θNO.
abstract: Whether the specific blood transfer conductance for nitric oxide (NO) with hemoglobin (θNO) is finite or infinite is controversial but important in the calculation of alveolar capillary membrane conductance (DmCO) and pulmonary capillary blood volume (VC) from values of lung diffusing capacity for carbon monoxide (DLCO) and nitric oxide (DLNO). In this review, we discuss the background associated with θNO, explore the resulting values of DmCOand VCwhen applying either assumption, and investigate the mathematical underpinnings of DmCOand VCcalculations. In general, both assumptions yield reasonable rest and exercise DmCOand VCvalues. However, the finite θNOassumption demonstrates increasing VC, but not DmCO, with submaximal exercise. At relatively high, but physiologic, DLNO/DLCO ratios both assumptions can result in asymptotic behavior for VCvalues, and under the finite θNOassumption, DmCOvalues. In conclusion, we feel that the assumptions associated with a finite θNOrequire further in vivo validation against an established method before widespread research and clinical use.
authors.affiliation: Mayo Graduate School, Mayo Clinic, 200 1(st) St. SW, Rochester, MN, USA.
authors.forename: Kirsten E
authors.initials: KE
authors.lastname: Coffman
authors.affiliation: Mayo Graduate School, Mayo Clinic, 200 1(st) St. SW, Rochester, MN, USA.
authors.forename: Steven C
authors.initials: SC
authors.lastname: Chase
authors.affiliation: Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, UK.
authors.forename: Bryan J
authors.initials: BJ
authors.lastname: Taylor
authors.affiliation: Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic, 200 1(st) St. SW, Rochester, MN, USA. Electronic address: Johnson.Bruce@mayo.edu.
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Johnson
mesh_terms: D000818:Animals; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D008955:Models, Cardiovascular; D009569:Nitric Oxide / Q000097:blood*; D011653:Pulmonary Diffusing Capacity
chemical_list: D006454:Hemoglobins; D009569:Nitric Oxide
keywords: Alveolar capillary membrane conductance; Exercise; In vivo validation; Lung diffusing capacity; Pulmonary capillary blood volume