Occlusion of cortical ascending venules causes blood flow decreases, reversals in flow direction, and vessel dilation in upstream capillaries
“…Blood Flow Decreases After Small Venule Strokes may be Damaging to Brain Cells
The extensive blood flow and vascular changes we observed after occlusion of single cortical AVs and SVs suggest that these occlusions may lead to dysfunction in brain cells. Previous work has shown that occlusion of large cortical veins leads to regional reductions in blood flow that causes ischemic infarction (Nakase et al, 1997b). We found that blood flow decreased to ~20% of baseline values within 100 µm of occluded AVs, which is at the level at which cellular inhibition of protein synthesis and energy failure begins to occur (Mies et al, 1991). These blood flow reductions are not sufficient to cause acute cell death, but, if protracted in time, may lead to brain dysfunction (Iadecola, 2010). This conclusion is supported by studies in the intestinal mesenteric circulation showing that venular occlusion lead to parenchymal cell death that increased with time (Takase et al, 1999). Furthermore, changes in vascular wall shear stress caused by changes in flow speed and direction could promote inflammation and oxidative stress in endothelial cells (Harrison et al, 2006). Finally, increased intravascular capillary pressures may lead to increased blood–brain barrier permeability (Mayhan et al, 1986), which can cause brain edema and inflammation (Mayhan et al, 1986; Rosenberg, 1999). Venous insufficiently has been associated with an increasing number of brain pathologies, ranging from multiple sclerosis to dementia (Black et al, 2009; Moody et al, 1995; Singh and Zamboni, 2009). Although the role of venous alterations in the pathogenesis of these conditions remains uncertain, these results show that venular occlusions have profound and widespread effects on brain microcirculation, highlighting the pathogenic potential of venous insufficiency….”
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Occlusion of cortical ascending venules causes blood flow decreases, reversals in flow direction, an
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The accumulation of small strokes has been linked to cognitive dysfunction. Although most animal models have focused on the impact of arteriole occlusions, clinical evidence indicates that venule occlusions may also be important. We used two-photon excited fluorescence microscopy to quantify changes...