Rapid onset of hypoxic vasoconstriction in isolated lungs.
A fast-response O2 analyzer that samples air at low flow rates allows the quasi-instantaneous measurement of O2 concentration change in the airways of isolated blood-perfused rat lungs. This instrument and an oximeter were used to measure the stimulus-response delay time of hypoxic pulmonary vasoconstriction when the lungs were challenged with 10, 5, or 3% O2. The estimate for the shortest delay time between accomplished fall in airway O2 concentration and the onset of hypoxia-induced vasoconstriction was approximately 7 s. We found that the slope of pressure rise, but not the stimulus-response delay time, correlated with the magnitude of hypoxic vasoconstriction. Oscillations in pulmonary arterial pressure were observed when the lungs were challenged with 10% O2 but not when the challenge was 12, 5, or 3%, indicating perhaps that these oscillations were a threshold phenomenon. Established hypoxic vasoconstriction was sensitive to brief changes in airway O2 concentration. Vasodilation occurred when the gas mixture was switched from 3 to 21% O2 for two to five breaths, and vasoconstriction occurred when the gas was changed during a single breath from 5 to 3% O2.
Jensen
K S
KS
Cardiovascular Pulmonary Research Laboratory, University of Colorado Health Sciences Center, Denver 80262.
Micco
A J
AJ
Czartolomna
J
J
Latham
L
L
Voelkel
N F
NF
D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D000860:Hypoxia / Q000503:physiopathology*; D066298:In Vitro Techniques; D008168:Lung / Q000503:physiopathology*; D008297:Male; D010100:Oxygen; D011652:Pulmonary Circulation / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D014661:Vasoconstriction / Q000502:physiology*
D010100:Oxygen