Premium
Sporadic coordinated shifts of regional ventilation and perfusion in juvenile pigs with normal gas exchange
Author(s) -
Robertson H. Thomas,
Neradilek Blazej,
Polissar Nayak L.,
Glenny Robb W.
Publication year - 2007
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2007.136358
Subject(s) - covariance , correlation , juvenile , chemistry , zoology , perfusion , interval (graph theory) , mathematics , nuclear medicine , medicine , biology , statistics , ecology , combinatorics , geometry
Repeated high‐resolution measurements of both regional pulmonary ventilation and regional blood flow (r) have revealed that ∼6 to 10% of the summed spatial and temporal heterogeneity can be attributed to spontaneous temporal variability. To test the hypothesis that the spontaneous temporal shifts of r and r are coordinated, 12 anaesthetized juvenile pigs had pairs of colours of aerosol and intravenous fluorescent microspheres (FMS) administered simultaneously at 20 min intervals to mark r and r. The animals were killed, the lungs inflated, air‐dried and cut into ∼2 cm 3 cubes. The concentrations of FMS colours from each cube, representing r and r at every 20 min interval, were measured with a fluorescence spectrophotometer. The correlation between per‐piece temporal shifts in r and r, calculated as the mean within‐piece covariance, was positive ( P < 0.001) for every temporally adjacent pair of measurements in every animal, although there were large differences in the magnitude of the mean temporal covariance among animals. The individual cubes with the most positive temporal covariance across all measurement periods usually demonstrated a large single‐interval coordinated shift of r and r, with average temporal covariance observed at the other intervals. The largest between‐interval shifts in r and r included equal proportions of coordinated increases and coordinated decreases. High‐resolution measurements of r and r acquired over 20 min intervals reveal that the overall positive correlation between temporal changes in r and r is driven by relatively infrequent large‐magnitude changes within small regions of the lung.