New optical method for analyzing cortical blood flow heterogeneity in small animals: validation of the method

Abstract

In pentobarbital-anesthetized male Sprague-Dawley rats, a small cranial window was trephined, and the cortex was transilluminated with a fine glass fiber inserted into the brain parenchyma. The light intensity at the surface area of 2 x 2 mm was recorded during intracarotid injection of 25 microl of carbon black (CB) solution. The region of interest (ROI) was divided into a 50 x 50 matrix, and the mean transit time of CB transport was calculated in each matrix element. We found rapid transits of CB along the microvasculature, with considerable heterogeneity in the avascular area, and heterogeneous efficiency in autoregulatory capacity in the ROI during hypotension. The method was validated by comparison with laser-Doppler flowmetry. The average mean difference was 0.03 +/- 0. 05%. Five percent CO(2) inhalation increased the flow by 85%, but heterogeneously. We concluded that the technique is exclusively sensitive to indicator transits in a very small area on the brain surface with potential usefulness in detecting regional heterogeneity in blood flow.

Image-based vessel-by-vessel analysis for red blood cell and plasma dynamics with automatic segmentation

“…It should be noted that a slightly faster speed was detected for the plasma in these vessels. This observation contradicts previous reports measured in the cerebral microcirculation (Lin et al, 1995;Rovainen et al, 2003;Schiszler et al, 2000). The contradiction may be due to differences in the vessel size and type investigated.…”

Oscillating neuro-capillary coupling during cortical spreading depression as observed by tracking of FITC-labeled RBCs in single capillaries

“…One of our findings was that the RBC velocity was often independent of upstream arteriolar blood flow or tissue perfusion in the surrounding microvasculature as measured with, for example, the tissue hemodilution technique (Schiszler et al, 2000). When local blood flow was dramatically increased by topical application of nitric oxide (NO) on the brain surface, the capillary RBC flow was unexpectedly rather decreased (Tomita et al, 2009a).…”

Initial Oligemia with Capillary Flow Stop Followed by Hyperemia during K+-Induced Cortical Spreading Depression in Rats

“…The optical method employed here was as reported elsewhere (Schiszler et al, 2000). A transillumination technique was applied, despite possible damage arising from optical fiber insertion into the brain tissue, because any changes in the light transmission (LT) at l ¼ 550710 nm, one of the isosbestic points of hemoglobin, are attributable to changes in cerebral blood volume (CBV) (Tomita M et al, 1978).…”

“…This communication describes a comprehensive examination of capillary flow changes in the cerebral cortex during K þ -induced CSD (neuronal depolarization) by employing a new optical method with a high spatial resolution which has recently been developed by us (Schiszler et al, 2000).…”