Did you know that our body shares a chemical reaction with sparkling water? Carbon dioxide’s interaction with water, which yields bicarbonate and protons, is a key element in processes such as gastric acid secretion and eye pressure maintenance. For efficiency, an enzyme called carbonic anhydrase (CA) resides in our body to speed up the reaction. However, excess activity of CA can make our body environment inhospitable for normal cellular functions. As a result, the World Health Organization deems carbonic anhydrase inhibitors (CAIs) important for basic healthcare treatment.
Glaucoma is one example wherein CA’s activity in the eyes goes wrong. Thomas H. Maren showed that bicarbonate ions are vital for the formation of aqueous humor which gives eyes proper shape and inner pressure. When the level of bicarbonate ions elevates due to over-activity of CAs, aqueous humor will build up and exert excess pressure on the optic nerve, causing decreased or lost vision.
Apart from treating glaucoma. CAI’s such as acetazolamide (Diamox) can also treat mountain sickness. At high altitude, people breathe more frequently due to a lack of oxygen. As a result, the body will deplete bicarbonate and protons, leading to metabolic alkalosis. This condition can be fatal in extreme cases due to a large spike in tissue pH. Therefore, Everest Base Camp suggests acetazolamide as the first drug to be used in the prevention of mountain sickness.
Source: Christian Nasca
However, CAIs also have adverse effects due to the omnipresence of both CAs and interconversion of bicarbonate ions and carbonic acids (illustrated below). Parietal cells in the stomach utilize protons generated in the interconversion to secret hydrochloric acid in gastric juice. Thus, as stated by glaucoma.org, CAIs can cause stomach pain. Moreover, the depletion of bicarbonate ions in the kidneys triggered by CAIs induces metabolic acidosis, a condition wherein excess acids float around in our body.
Although the pros and cons of CAIs were explored last century, research on other aspects is thriving. Various studies have shown that cancer cells and some pathogenic bacteria need specific CAs for their virulent activities. Selective CAIs are not only possible remedies for cancers but novel drugs against malignant diseases such as malaria, stomach ulcers and tuberculosis.
Next time when you pop open a soda, appreciate the important reaction inside!
Feature Image Source: Mike Mozart
