Lung inflation distends small arteries (< 1 mm) in excised dog lungs.
We utilized microfocal fluoroscopic angiography to study the influence of lung inflation on small (0.2- to 1.3-mm-diam) pulmonary arteries in isolated left lower lobes from dog lungs during both flow and no-flow conditions. Alveolar pressure, which in this preparation was equal to transpulmonary pressure, was set at 2, 8, or 14 mmHg while vascular pressure was varied from 0 to 24 mmHg. The diameters of these small arterial vessels increased with lung inflation. No differences were observed between the results obtained during flow and no-flow conditions. Thus, arteries in this diameter range can be considered as extra-alveolar, and the effect of lung inflation on these small extra-alveolar arteries was qualitatively similar to that previously described for larger extra-alveolar vessels. Quantitatively, the degree of vessel distension was about the same per unit increase in transpulmonary pressure at constant vascular pressure as for a change in vascular pressure at constant transpulmonary pressure. Accordingly, inflation produced a decrease in perivascular pressure surrounding these small arteries that was approximately equal to the increase in transpulmonary pressure.
Albert
R K
RK
Department of Veterans Affairs Medical Center, Seattle, Washington.
Lamm
W J
WJ
Rickaby
D A
DA
al-Tinawi
A
A
Dawson
C A
CA
D000399:Air Pressure; D000792:Angiography; D000818:Animals; D001160:Arterioles / Q000033:anatomy & histology / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D004285:Dogs; D066298:In Vitro Techniques; D008168:Lung / Q000502:physiology*; D008176:Lung Volume Measurements; D011651:Pulmonary Artery / Q000033:anatomy & histology / Q000502:physiology*; D015656:Respiratory Mechanics / Q000502:physiology*