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Between‐ and within‐animal variation of CBF during hypotension and ischemia in relation to eNOS concentration, [eNOS], in the rat brain
Journal article   Open access   Peer reviewed

Between‐ and within‐animal variation of CBF during hypotension and ischemia in relation to eNOS concentration, [eNOS], in the rat brain

Stephen C. Jones and Alexander Kharlamov
The FASEB journal, v 20(4), pp A721-A722
Mar 2006
DOI: https://doi.org/10.1096/fasebj.20.4.A721
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https://doi.org/10.1096/fasebj.20.4.a721View
Published, Version of Record (VoR)Maybe Open Access (Publisher Bronze),  Open

Abstract

Variations in the CBF response to hypotension and focal ischemia have been reported. Nitric oxide from eNOS is a possible candidate as the regulatory factor during these conditions. We hypothesize that regional heterogeneity as well as between‐animal variations in CBF during hypotension and ischemia are dependent on [eNOS]. Hemorrhagic hypotension (70 mmHg, n = 4) and focal ischemia (permanent left MCA and bilateral CCA occlusions, n = 2) were produced in anesthetized (isoflurane) Sprague/Dawley rats. CBF measurement was performed with laser speckle flowmetry (LSF) before and during hypotension, and before and 15 min after ischemia. In each region‐of‐interest (ROI) %CBFhypotension and %CBFischemia as % of CBF before hypotension and ischemia, respectively, were calculated. The head was frozen while still in the stereotactic frame. Micropunch samples (2‐0.5 mg) were taken and run in duplicate on 10% SDS PAGE followed by quantitative Western blot analysis using recombinant eNOS protein as a standard. Retrospective measurement of CBF in the exact same ROIs where micropunch samples were taken showed strong negative correlation (r2 = 0.81, p = 0.014) between median %CBFhypotension and median [eNOS] during hypotension (Fig. A). Negative correlation between %CBFischemia and [eNOS] was also observed within the ischemic hemispheres in each animal 15 min after ischemia (r2 = 0.04 and 0.14, Fig. B). We conclude that lower flow is associated with higher [eNOS] between animals during hypotension and regionally, within animals, during focal ischemia, based on the more intense hypotensive stimulus during focal ischemia. The results agreed with those obtained by other workers using eNOS immunohistochemistry in both hypotension and focal ischemia.

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