Baking soda

Baking soda aids photoreceptor cell recovery

A new study determines a common chemical compound many people associate with baking and cellular processes could affect the visual signals generated by rod and cone photoreceptors.

"This work raises the implication that high bicarbonate levels could also potentially raise cGMP to dangerous levels in our rods and cones."

Researchers from the Massachusetts Eye and Ear/Harvard Medical School and Salus University recently published a study in the Journal of Biological Chemistry that posited bicarbonate-commonly referred to as baking soda (sodium bicarbonate)—could impact vision and certain forms of retinal diseases by changing the metabolic states of retinal cells.  

According to the study, as light interacts with rod and cone photoreceptors, a biochemical reaction takes place and a small soluble molecule, cGMP, is destroyed. As darkness returns, the concentration of this molecule rises again. Bicarbonate was found to directly stimulate an enzyme that produces cGMP.  

The study's lead author, Clint Makino, Ph.D., associate professor of ophthalmology at Harvard Medical School, said in a news release that "by opposing the effect of light, bicarbonate limits the size of the photon response and quickens its recovery ... (and) as a result, sensitivity to light is slightly lower but our ability to track moving objects is improved."  

Researchers plan to continue their study to determine if controlling bicarbonate levels could slow progression of certain eye diseases that result in destroyed photoreceptor cells.  

Dangerous in excess  
Andrew Hartwick, O.D., Ph.D., associate professor at The Ohio State University College of Optometry, in reviewing the study says it has been well established that calcium regulates the recovery of cGMP levels that occurs with the switch from light to dark, and this study has identified another in the form of bicarbonate.  

Dr. Hartwick adds that too much cGMP in rods and cones can be toxic, however, and this is thought to contribute to the degeneration that occurs in some forms of retinitis pigmentosa. Bicarbonate—produced at a cellular level through the conversion of CO2—in excessive levels can do more harm than good, such as when deep-sea SCUBA divers rapidly ascend to the surface, he says.  

"This work raises the implication that the high bicarbonate levels associated with these situations could also raise cGMP to dangerous levels in our rods and cones, but this remains to be determined," Dr. Hartwick stated.

April 21, 2015

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