A team of researchers from Johns Hopkins Medicine (Baltimore, MD) has discovered a receptor on blood vessels that causes the vessel to relax in response to blue light, making it potentially useful in treating vascular diseases.
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The researchers—led by senior author Dan Berkowitz, MD, a professor in the Department of Anesthesiology and Critical Care Medicine—looked for expression of a light receptor in the blood vessels of mice and discovered a receptor called melanopsin, or opsin 4—one of a group of non-image-forming light receptors. In mice without opsin 4, blood vessels did not relax in response to light.
Upon further study, Berkowitz and his team were able to determine the exact wavelength (455 nm) at which opsin 4 is activated and the blood vessel relaxation response is maximal. The scientists could use this wavelength-specific light to increase blood flow in the tails of normal mice, but not in the tails of mice that lacked expression of opsin 4.
It will be important to determine if this phenomenon is present across all species and in all vascular beds, and to uncover all of the signaling and regulatory mechanisms that are linked to the receptor. Also, investigators will want to know if problems associated with the receptor are present in patients with vascular disease.
Berkowitz sees a variety of applications for his research. For example, his group hopes to target the opsin 4 receptor with wavelength-specific light as a therapeutic option for Raynaud's phenomenon, which is characterized by exaggerated vasoconstriction of the vessels of the fingers and toes. "We plan to use high-intensity light-emitting diodes, or LEDs, incorporated into gloves as a potential mode of therapy for these patients. Additionally, socks with LEDs could be used in diabetic patients to potentially enhance blood flow and heal chronic ischemic ulcers."
Full details of the work appear in the Proceedings of the National Academy of Sciences; for more information, please visit http://bit.ly/1wYgypv.
(Thumbnail image via Shutterstock)
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