Featured Research

from universities, journals, and other organizations

Viagra, Unlikely Tool For Vision Research, Slows The Visual Response To Flickering Light

Date:
January 23, 2006
Source:
Cell Press
Summary:
Therapeutic doses of Viagra® have been shown to influence the rate at which visual signals are integrated by the brain, affecting the way quick, repeated events, such as flickering light, are perceived. The work sheds light on the function of a specific photoreceptor enzyme and paves the way for future research utilizing Viagra as a safe tool for studying human vision.

Therapeutic doses of Viagra® have been shown to influence the rate at which visual signals are integrated by the brain, affecting the way quick, repeated events, such as flickering light, are perceived. The work sheds light on the function of a specific photoreceptor enzyme and paves the way for future research utilizing Viagra as a safe tool for studying human vision.

Originally developed as a heart drug, sildenafil citrate (Viagra®) has several side effects, not least of which is that it helps to alleviate erectile dysfunction by prolonging the relaxation of smooth muscle in the corpora cavernosa of the penis, thereby helping to maintain the blood flow required for an erection. A less desirable side effect is that it inhibits the enzyme phosphodiesterase, PDE6, which is in the cone and rod photoreceptors of the eye and is involved in the transduction of photons into neural signals that are decoded by the visual system. The precise effect of Viagra on human visual performance, however, remains somewhat equivocal and anecdotal.

By measuring the ability of human observers to detect flickering lights under various conditions, a team of researchers, including Andrew Stockman of the Institute of Ophthalmology, London, has demonstrated that therapeutic 100 mg doses of Viagra cause transient losses in the sensitivity to flicker. These losses range in severity, from mild to moderate, among observers. In those more affected observers, the losses in flicker sensitivity caused by the inhibition of PDE6 by Viagra are consistent with an almost doubling of the time over which visual events are integrated by the visual system.

These results demonstrate the importance of PDE6 not only in transduction, but also in light adaptation: PDE6 normally helps to maintain the visual response within an optimal range by shortening the time over which visual responses are integrated as the light level increases. When the integration time is not appropriately reduced with light level--for example, owing to the inhibition of PDE6 by Viagra--the integrated visual response becomes too large and the eye's temporal resolution too low. Thanks to these detrimental effects, Viagra represents a unique tool for the scientist to manipulate the activity of PDE6 pharmacologically in humans in vivo, and thus to investigate the role of this enzyme in vision.

###

The researchers include Andrew Stockman, Lindsay T. Sharpe, and Glen Jeffery of the University College London in London, United Kingdom; Adnan Tufail of Moorfields Eye Hospital in London, United Kingdom; Philip D. Kell of Middlesex Hospital in London, United Kingdom. This work was supported by a Wellcome Trust awarded to A.S.

Stockman et al.: "Viagra slows the visual response to flicker." Current Biology 16, pages R44-R45, January 24, 2006 DOI 10.1016/j.cub.2006.01.016 www.current-biology.com


Story Source:

The above story is based on materials provided by Cell Press. Note: Materials may be edited for content and length.


Cite This Page:

Cell Press. "Viagra, Unlikely Tool For Vision Research, Slows The Visual Response To Flickering Light." ScienceDaily. ScienceDaily, 23 January 2006. <www.sciencedaily.com/releases/2006/01/060123164756.htm>.
Cell Press. (2006, January 23). Viagra, Unlikely Tool For Vision Research, Slows The Visual Response To Flickering Light. ScienceDaily. Retrieved April 18, 2014 from www.sciencedaily.com/releases/2006/01/060123164756.htm
Cell Press. "Viagra, Unlikely Tool For Vision Research, Slows The Visual Response To Flickering Light." ScienceDaily. www.sciencedaily.com/releases/2006/01/060123164756.htm (accessed April 18, 2014).

Share This



More Health & Medicine News

Friday, April 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Obama: 8 Million Healthcare Signups

Obama: 8 Million Healthcare Signups

AP (Apr. 17, 2014) — President Barack Obama gave a briefing Thursday announcing 8 million people have signed up under the Affordable Care Act. He blasted continued Republican efforts to repeal the law. (April 17) Video provided by AP
Powered by NewsLook.com
Is Apathy A Sign Of A Shrinking Brain?

Is Apathy A Sign Of A Shrinking Brain?

Newsy (Apr. 17, 2014) — A recent study links apathetic feelings to a smaller brain. Researchers say the results indicate a need for apathy screening for at-risk seniors. Video provided by Newsy
Powered by NewsLook.com
Could Even Casual Marijuana Use Alter Your Brain?

Could Even Casual Marijuana Use Alter Your Brain?

Newsy (Apr. 16, 2014) — A new study conducted by researchers at Northwestern and Harvard suggests even casual marijuana use can alter your brain. Video provided by Newsy
Powered by NewsLook.com
Thousands Of Vials Of SARS Virus Go Missing

Thousands Of Vials Of SARS Virus Go Missing

Newsy (Apr. 16, 2014) — A research institute in Paris somehow misplaced more than 2,000 vials of the deadly SARS virus. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins