AJP - Regulatory, Integrative and Comparative Physiology, Vol 249, Issue 4 482-R489, Copyright © 1985 by American Physiological Society
Rete mirabile of goat: its flow-damping effect on cerebral circulation
S. Lluch, G. Dieguez, A. L. Garcia and B. Gomez
This work was designed to characterize in anesthetized goats the
hemodynamic response of the carotid rete during pharmacologically induced
changes in systemic blood pressure or blood flow to the brain. Under
control conditions, mean blood pressure in the middle cerebral artery
(distal to rete) was 18% lower than that measured in the internal maxillary
artery (proximal to rete). Pressure gradient and calculated resistance
across the rete were unchanged when systemic arterial pressure was
increased or decreased by intravenous administration of norepinephrine or
isoproterenol, respectively. Hypercapnia or injections of isoproterenol and
acetylcholine into the internal maxillary arteries increased blood flow and
decreased middle cerebral arterial pressure, whereas injections of
norepinephrine decreased blood flow and increased postrete pressure.
Calculated resistance across the rete was unchanged. These observations
indicate that the response of the carotid rete to the substances tested is
negligible; they also suggest that the carotid rete may have a flow-damping
effect by maintaining resistance to blood flow when a change in the caliber
of brain vessels occurs.
