In:
eLife, eLife Sciences Publications, Ltd, Vol. 7 ( 2018-03-21)
Abstract:
Blood vessels in animals’ bodies are highly organized. The large blood vessels from the heart branch to smaller vessels that are spread throughout the tissues. The smallest vessels, the capillaries, allow oxygen and nutrients to pass from the blood to nearby cells in tissues. Some capillaries, including those at the back of the eye (in the retina) and those in the brain, change their diameter in response to activity in the nervous system. This allows more or less oxygen and nutrients to be delivered to match these tissues’ demands. However, unlike for larger blood vessels, how capillaries constrict or dilate is debated. While large vessels are encircled by smooth muscle cells, capillaries are instead surrounded by muscle-like cells called pericytes, and some scientists have suggested that it is these cells that contract to narrow the diameter of a capillary or relax to widen it. However, other researchers have questioned this explanation. This is mostly because several laboratories could not detect the proteins that would be needed for contraction within these pericytes – the most notable of which is a protein called α-smooth muscle actin (or α-SMA for short). Alarcon-Martinez, Yilmaz-Ozcan et al. hypothesized that the way samples are usually prepared for analysis was causing the α-SMA to be degraded before it could be detected. To test this hypothesis, they used different methods to fix and preserve capillaries and pericytes in samples taken from the retinas of mice. When the tissue samples were immediately frozen with ice-cold methanol instead of a more standard formaldehyde solution, α-SMA could be detected at much higher levels in the capillary pericytes. Treating samples with a toxin called phalloidin, which stabilizes filaments of actin, also made α-SMA more readily visible. When α-SMA was experimentally depleted from the mouse retinas, the capillary pericytes were more affected than the larger blood vessels. This finding supports the idea that the pericytes contain, and rely upon, only a small amount of α-SMA. Finding α-SMA in capillary pericytes may explain how these small blood vessels can change their diameter. Future experiments will clarify how these pericytes regulate blood flow at the level of individual capillaries, and may give insights into conditions such as stroke, which is caused by reduced blood flow to the brain.
Type of Medium:
Online Resource
ISSN:
2050-084X
DOI:
10.7554/eLife.34861.001
DOI:
10.7554/eLife.34861.002
DOI:
10.7554/eLife.34861.003
DOI:
10.7554/eLife.34861.004
DOI:
10.7554/eLife.34861.005
DOI:
10.7554/eLife.34861.006
DOI:
10.7554/eLife.34861.007
DOI:
10.7554/eLife.34861.008
DOI:
10.7554/eLife.34861.009
DOI:
10.7554/eLife.34861.010
DOI:
10.7554/eLife.34861.011
DOI:
10.7554/eLife.34861.012
DOI:
10.7554/eLife.34861.013
DOI:
10.7554/eLife.34861.014
DOI:
10.7554/eLife.34861.016
DOI:
10.7554/eLife.34861.017
Language:
English
Publisher:
eLife Sciences Publications, Ltd
Publication Date:
2018
detail.hit.zdb_id:
2687154-3
Permalink