title: Pulmonary vascular resistance distribution and recruitment of microvascular surface area.
abstract: To test the hypothesis that the distribution of hemodynamic resistance is involved in the control of pulmonary capillary surface area, we measured permeability-surface area product (PS) and longitudinal resistance distribution (LRD) as functions of perfusion rate in isolated rabbit lungs under zone II conditions (n = 10) and through the zone II-III transition (n = 4). PS, considered to be indicative of functioning capillary surface area, was measured with the aid of the diffusion-limited tracer [14C]propanediol, whereas LRD was determined using a viscous bolus technique. LRD was seen to change character with increasing flow and increasing PS/surface area, becoming bimodal with low central resistance as full capillary recruitment was approached in zone III. Effects of hypoxic ventilation were studied in zone II in five lungs; it was found that hypoxia altered the LRD and eradicated the normoxic dependence of PS/surface area on perfusion rate. It was concluded that LRD is involved in the determination of functioning capillary surface area.
authors.affiliation: Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee 37235.
authors.forename: K A
authors.initials: KA
authors.lastname: Overholser
authors.forename: N A
authors.initials: NA
authors.lastname: Lomangino
authors.forename: R E
authors.initials: RE
authors.lastname: Parker
authors.forename: N A
authors.initials: NA
authors.lastname: Pou
authors.forename: T R
authors.initials: TR
authors.lastname: Harris
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D002196:Capillaries / Q000502:physiology; D002199:Capillary Permeability / Q000502:physiology; D015633:Extravascular Lung Water / Q000502:physiology; D000860:Hypoxia / Q000503:physiopathology; D066298:In Vitro Techniques; D008168:Lung / Q000098:blood supply*; D011409:Propylene Glycols; D011817:Rabbits; D014655:Vascular Resistance / Q000502:physiology*; D014661:Vasoconstriction / Q000502:physiology; D014783:Viscosity
chemical_list: D011409:Propylene Glycols