title: Unaltered pulmonary capillary surface area in the presence of changing arterial resistance.
abstract: We hypothesized that capillary recruitment may not be solely dependent on extracapillary factors. To test this hypothesis, rabbits were anesthetized and placed on total cardiac bypass at a constant, physiological pulmonary blood flow. Vascular occlusion techniques were combined with measurement of the transpulmonary metabolism of an angiotensin-converting enzyme substrate, allowing the concomitant assessment of changes in segmental resistances and dynamically perfused capillary surface area. Intra-arterial serotonin infusion increased upstream pulmonary vascular resistances without affecting dynamically perfused capillary surface area. Intra-arterial isoproterenol infusion diminished serotonin-induced increased upstream resistances, also without affecting capillary surface area. These findings support the hypothesis that pulmonary capillary recruitment may not be solely dependent on extracapillary factors.
authors.affiliation: Department of Pediatrics, Medical College of Georgia, Augusta 30912, USA.
authors.forename: L E
authors.initials: LE
authors.lastname: Fisher
authors.forename: A
authors.initials: A
authors.lastname: Cziraki
authors.forename: C M
authors.initials: CM
authors.lastname: Steinhart
authors.forename: J D
authors.initials: JD
authors.lastname: Catravas
mesh_terms: D000818:Animals; D002196:Capillaries / Q000502:physiology; D002200:Capillary Resistance / Q000187:drug effects / Q000502:physiology*; D006976:Hypertension, Pulmonary / Q000503:physiopathology; D007545:Isoproterenol / Q000494:pharmacology; D008833:Microcirculation; D011652:Pulmonary Circulation / Q000502:physiology*; D011817:Rabbits; D012701:Serotonin / Q000494:pharmacology; D013499:Surface Properties
chemical_list: D012701:Serotonin; D007545:Isoproterenol