Delayed hypovolemic hypotension exacerbates the hemodynamic and histopathologic consequences of thromboembolic stroke in rats.
Abnormalities in cerebrovascular reactivity or hemodynamic reserve are risk factors for stroke. The authors determined whether hemodynamic reserve is reduced in an experimental model of thromboembolic stroke. Nonocclusive common carotid artery thrombosis (CCAT) was produced in rats by a rose bengal-mediated photochemical insult, and moderate hypotension (60 mm Hg/30 min) was induced 1 hour later by hemorrhage. Alterations in local cerebral blood flow (ICBF) were assessed immediately after the hypotensive period by 14C-iodoantipyrine autoradiography, and histopathologic outcome was determined 3 days after CCAT. Compared to normotensive CCAT rats (n = 5), induced hypotension after CCAT (n = 7) led to enlarged regions of severe ischemia (i.e., mean ICBF < 0.24 mL/g/min) in the ipsilateral hemisphere. For example, induced hypotension increased the volume of severely ischemic sites from 16 +/- 4 mm3 (mean +/- SD) to 126 +/- 99 mm3 (P < 0.05). Histopathologic data also showed a larger volume of ischemic damage with secondary hypotension (n = 7) compared to normotension (22 +/- 15 mm3 versus 5 +/- 5 mm3, P < .05). Both hypotension-induced decreases in ICBF and ischemic pathology were commonly detected within cortical anterior and posterior borderzone areas and within the ipsilateral striatum and hippocampus. In contrast to CCAT, mechanical ligation of the common carotid artery plus hypotension (n = 8) did not produce significant histopathologic damage. Nonocclusive CCAT with secondary hypotension therefore predisposes the post-thrombotic brain to hemodynamic stress and structural damage.
Dietrich
W D
WD
Department of Neurology, University of Miami School of Medicine, Florida 33101, USA.
Prado
R
R
Pravia
C
C
Zhao
W
W
Ginsberg
M D
MD
Watson
B D
BD
D000818:Animals; D001794:Blood Pressure; D001921:Brain / Q000098:blood supply / Q000473:pathology / Q000503:physiopathology*; D002245:Carbon Dioxide / Q000097:blood; D002341:Carotid Artery Thrombosis / Q000150:complications* / Q000473:pathology / Q000503:physiopathology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D007839:Functional Laterality; D006439:Hemodynamics / Q000502:physiology*; D007022:Hypotension / Q000150:complications / Q000473:pathology / Q000503:physiopathology; D008297:Male; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D051381:Rats; D017208:Rats, Wistar; D012016:Reference Values; D012039:Regional Blood Flow; D012307:Risk Factors; D012769:Shock / Q000150:complications* / Q000473:pathology / Q000503:physiopathology*
D002245:Carbon Dioxide; D010100:Oxygen