Journal of Applied Physiology, Vol 60, Issue 3 959-964, Copyright © 1986 by American Physiological Society
Mechanisms by which dopamine alters blood flow distribution during lobar collapse in dogs
J. P. Gardaz, P. A. McFarlane and M. K. Sykes
Dopamine increases blood flow to a hypoxic left lower lobe in dogs. To
elucidate possible mechanisms, left lower lobe collapse was induced in
anesthetized dogs, and lobar (QLLL) and total (QT) pulmonary blood flow was
measured by electromagnetic flow probes. Dopamine infusion increased mean
pulmonary arterial pressure (Ppa), QT, and QLLL. However, the increase in
QLLL was double that produced by a similar increase in Ppa without increase
in QT (inflation of a Swan-Ganz balloon in right pulmonary artery) or by a
similar increase in QT with smaller increase in Ppa (opening of
arteriovenous fistulas). QLLL/QT was not changed by opening arteriovenous
fistulas, but was increased by Swan-Ganz balloon inflation, and by infusion
of dopamine. It is concluded that the increase in QLLL/QT produced by
dopamine was due to a decrease in hypoxic vasoconstriction in the lobe
secondary to an increase in mixed venous PO2 and to vasoconstriction in the
oxygenated lung.
