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Reactivity of Brain Parenchymal Arterioles after Ischemia and Reperfusion
Author(s) -
CIPOLLA MARILYN J.,
BULLINGER LISA V.
Publication year - 2008
Publication title -
microcirculation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.793
H-Index - 83
eISSN - 1549-8719
pISSN - 1073-9688
DOI - 10.1080/10739680801986742
Subject(s) - nifedipine , arteriole , ischemia , medicine , microcirculation , cardiology , parenchyma , middle cerebral artery , anesthesia , lumen (anatomy) , blood flow , cerebral blood flow , contraction (grammar) , pathology , calcium
Objective: We investigated the effect of ischemia and reperfusion on the vasoactive function of penetrating brain parenchymal arterioles under pressurized conditions. Methods: Parenchymal arterioles (<50 μm in diameter) from within the middle cerebral artery territory were dissected from male Wistar rats that were either nonischemic control (n = 16) or ischemic for one hour and reperfused for 24 hours (n = 16) by temporary filament occlusion of the middle cerebral artery. Arterioles were mounted on glass cannulas within an arteriograph chamber that allowed for the measurement of lumen diameter and control over intravascular pressure. Results: After one hour of equilibration at 10 mmHg, spontaneous myogenic tone developed in both groups of animals, constricting control arterioles from 69 ± 9 to 49 ± 11 μm (29.5 ± 10.2%) and ischemic arterioles from 66 ± 9 to 45 ± 11 μm (33.1 ± 14.1%); p > 0.05. Contraction to the nitric oxide synthase inhibitor nitro‐L‐arginine (10 –4 M) was significantly diminished in ischemic arterioles, constricting only 3.2 ± 3.3 vs. 15.6 ± 12.5% in control arterioles (p = 0.017). Both groups dilated to nifedipine; however, the response was significantly diminished after ischemia. The EC 50 for nifedipine in control arterioles was 3.54 ± 0.11 vs. 9.90 ± 0.71 nM for ischemic arterioles (p = 0.024). Conclusions: These findings demonstrate that functional changes occur in brain parenchymal arterioles after ischemia and reperfusion, a result that may significantly influence stroke outcome by altering blood flow to an ischemic region.