Litmus Test

By Suzanne D. Vernon, PhD, Scientific Director

The litmus test is one of the oldest methods for testing pH to determine the acidity or base of a substance. A research team from University of Newcastle published a paper titled, “Abnormalities in pH handling by peripheral muscle and potential regulation by the autonomic nervous system in chronic fatigue syndrome” in the Journal of Internal Medicine. Senior author Julia L. Newton has published a number of quality papers describing autonomic nervous system (ANS) abnormalities in CFS. In this current publication, her team attempts to understand some of the mechanisms that may be responsible for post-exertion physical fatigue and ANS abnormalities that are common in CFS patients. Based on knowledge of exercise physiology obtained from healthy individuals, they determined how muscles in 16 CFS patients handled protons, compared to eight sex- and age-matched controls. Here is what they found.

When muscles work during exercise, a temporary acid (low pH) environment is created because the muscle cells pump out protons. Pumping out protons is known as “proton efflux” and it requires cellular energy in the form of ATP. Healthy muscles are able to quickly equilibrate to a neutral pH once the work is complete.

Dr. Newton’s team used magnetic resonance spectroscopy (MRS) coupled with an exercise paradigm to determine how muscle protons were behaving in CFS and controls. All subjects performed plantar flexion (bending the foot at the ankle) while in the imaging scanner and photophlethysmography was used to assess heart rate variability. The control subjects displayed normal muscle physiology with a decrease in proton efflux over time following plantar flexion. On the other hand, CFS patients had abnormal proton efflux that was significantly suppressed following exercise and significantly prolonged. This suggests significant impairment in proton handling and muscle recovery kinetics. The normal proton efflux observed in healthy controls closely correlated with heart rate variability indicated a relationship with muscle pH. However, this relationship between pH and heart rate variability was lost in CFS patients.

I am intrigued by this study because it uses powerful imaging technology to measure basic physiology processes that are necessary for proper muscle function, coupled with an exercise paradigm to assess this function – a noninvasive assessment at the atomic level – how cool is that! These investigators documented a significant difference in the way that muscle in CFS patients handles protons compared to healthy controls. This correlated with ANS dysfunction in the CFS patients. Why CFS patients have this inability to efficiently pump out protons is not known, but the resultant physiologic imbalance could be sending inappropriate signals that are picked up by the ANS and causing the autonomic disturbances that many CFS patients experience. I also like this paper because it may help explain some of the other research that we have heard about lately (and that the Association funds!) including the elevated lactate in the brain cerebrospinal fluid and the blood ion channel receptors.

Reference

Abnormalities in pH handling by peripheral muscle and potential regulation by the autonomic nervous system in chronic fatigue syndrome D.E.J. Jones, K.G. Hollingsworth , R. Taylor, A.M. Blamire & J.L. Newton. J Intern Med 2010; 267: 394–401.

Suzanne Vernon, PhD, is the Association’s scientific director. She has nearly two decades of experience as a microbiologist.

May 1, 2010