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Threshold Duration of Ischemia for Myogenic Tone in Middle Cerebral Arteries
- Source :
- Stroke. 32:1658-1664
- Publication Year :
- 2001
- Publisher :
- Ovid Technologies (Wolters Kluwer Health), 2001.
-
Abstract
- Background and Purpose —We investigated the effect of different periods of ischemia on the myogenic tone of middle cerebral arteries (MCAs) and tested the hypothesis that ischemia disrupts the actin cytoskeleton in vascular smooth muscle. Methods —The MCA occlusion model was used in male Wistar rats (n=27) to induce different periods of ischemia (15, 30, and 120 minutes) with 24 hours of reperfusion. Successful occlusion was determined by laser-Doppler flowmetry. MCAs were then studied in vitro with a specialized arteriograph system that allowed control of transmural pressure and measurement of lumen diameter. After equilibration for 1 hour at transmural pressure of 75 mm Hg, lumen diameter was measured, and the amount of spontaneous myogenic tone was determined. Arteries were then fixed with 10% formalin while still pressurized in the arteriograph bath and stained for filamentous (F-) actin with fluorescently labeled phalloidin, a specific probe for F-actin. The amount of F-actin was quantified by confocal microscopy. Results —The amount of tone was similar between control and 15 minutes of ischemia (27.0±2.0% and 25.3±1.7%, respectively; P >0.05) but was significantly diminished after 30 and 120 minutes (11.7±2.0% and 8.5±2.0%, respectively; P P =0.04) such that the lesser the tone, the lesser was the F-actin content. Fluorescence intensity for control and 15, 30, and 120 minutes of ischemia was (×10 7 ) 3.21±0.25, 2.54±0.32 ( P >0.05), 2.32±0.15 ( P P Conclusions —These results demonstrate that ischemia disrupts the actin cytoskeleton in smooth muscle and diminishes vascular tone of MCAs in a threshold-dependent manner. This effect likely exacerbates brain tissue damage during stroke, including infarction and edema formation.
- Subjects :
- Male
Middle Cerebral Artery
medicine.medical_specialty
Vascular smooth muscle
Phalloidin
Cerebral arteries
Ischemia
Muscle, Smooth, Vascular
Brain Ischemia
chemistry.chemical_compound
Internal medicine
medicine.artery
medicine
Animals
Rats, Wistar
Cytoskeleton
Advanced and Specialized Nursing
Vascular disease
business.industry
Models, Cardiovascular
Infarction, Middle Cerebral Artery
Anatomy
medicine.disease
Actin cytoskeleton
Actins
Rats
Kinetics
chemistry
Muscle Tonus
Reperfusion Injury
Middle cerebral artery
Cardiology
Neurology (clinical)
Cardiology and Cardiovascular Medicine
business
Reperfusion injury
Subjects
Details
- ISSN :
- 15244628 and 00392499
- Volume :
- 32
- Database :
- OpenAIRE
- Journal :
- Stroke
- Accession number :
- edsair.doi.dedup.....123dd26f74b3f497fc912794c1c7107c