Flow/shear stress-induced responses are opposite in cerebral arteries of different locations
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1
University of Pécs, Department of Pathophysiology and Gerontology, Hungary
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2
University of Pécs, Department of Neurology, Hungary
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3
New York Medical College, Department of Physiology, United States
Introduction: It has been well established that increases in flow/shear stress elicit dilations in small arteries and arterioles of most tissues. However, vasomotor responses of cerebral vessels to increases in flow have not yet been established. It is also know that cerebral volume is tightly regulated. Thus we hypothesized that vasomotor responses of cerebral arteries of different locations will be different to increases in intraluminal flow/shear stress.
Methods: Isolated middle cerebral arteries (MCA) and basilar arteries (BA) of rats were studied in pressure-flow chamber. Changes of inner diameter were measured by a microangiometer to stepwise increases in intraluminal flow (at a constant intraluminal pressure of 80 mmHg) and wall shear stress (WSS) was calculated. Intraluminal flow was established by increasing the pressure difference throughout the vessels (ΔP = up to 40 or 60 mmHg). Finally, the passive diameters of vessels (in Ca2+ free solution) were measured.
Results: The active diameters of MCA and BA were 181±6 and 328±19μm, whereas the passive diameters were 295±9 and 419±14μm, respectively. In response to increases in flow the calculated WSS increased, yet the diameter of MCA decreased significantly (max. at ΔP = 40 mmHg: ~11%, p<0.05). In contrast, increases in flow, which increased calculated WSS elicited increases in the diameter of BA (max. at ΔP = 60 mmHg: ~8%, p<0.05). As a result of the constriction WSS increased exponentially further in MCA, whereas in BA the dilation limited the increase in WSS.
Conclusion: We propose that the opposite responses of cerebral arteries to increases in wall shear stress have important physiological roles: dilations of BA could be important to amplify the increase in blood flow to the brain, whereas constrictions of MCA could be important to maintain constant local cerebral volume.
Grants: Hungarian Nat. Sci. Res. Fund.-OTKA K71591, K67984, AHA Founders Aff., 0555897T, Hungarian Neuroimaging Foundation.
Conference:
IBRO International Workshop 2010, Pécs, Hungary, 21 Jan - 23 Jan, 2010.
Presentation Type:
Poster Presentation
Topic:
Homeostatic and neuroendocrine systems
Citation:
Springo
Z,
Toth
P,
Komoly
S and
Koller
A
(2010). Flow/shear stress-induced responses are opposite in cerebral arteries of different locations.
Front. Neurosci.
Conference Abstract:
IBRO International Workshop 2010.
doi: 10.3389/conf.fnins.2010.10.00130
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Received:
28 Apr 2010;
Published Online:
28 Apr 2010.
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Correspondence:
Zsolt Springo, University of Pécs, Department of Pathophysiology and Gerontology, Pécs, Hungary, springozsolt@yahoo.com