Journal of Applied Physiology, Vol 49, Issue 1 73-78, Copyright © 1980 by American Physiological Society
Pulmonary venoconstriction caused by elevated cerebrospinal fluid pressure in the dog
M. B. Maron and C. A. Dawson
Previously we found that raising cerebrospinal fluid pressure (PCSF) caused
pulmonary vasoconstriction mediated by adrenal catecholamines. To localize
the site of this vasoconstriction we used the outflow occlusion technique
to divide changes in the pulmonary arteriovenous pressure gradient (Pa-v)
into upstream and downstream pressure drops. Experiments were conducted in
10 dogs in which the animal's left lower lung lobe was denervated and
perfused at constant flow and outflow pressure with blood pumped from the
dog's pulmonary artery. Raising PCSF to 218 Torr caused Pa-v to rise from
9.0 to 12.5 Torr. Most (83%) of this increase resulted from an increase in
the downstream pressure drop. Previous studies have indicated that changes
in the upstream and downstream pressure drops, as measured by this
technique, are highly correlated with changes in the resistance of the
arterial and venous sides of the vascular bed. Thus, it appears that
elevated PCSF caused primarily pulmonary venoconstriction. Similar results
were obtained with norepinephrine and epinephrine infusion. This is
consistent with previous studies, indicating that adrenal catecholamines
are responsible for the increase in Pa-v in response to PCSF in this
preparation.
