Systemic extracellular acidification is a hallmark of ageing

Despite being essential for physiology at all levels, the behaviour of protons in bodily fluids is understudied in ageing. Here, we investigate how extracellular pH changes with age and its impact on longevity, using Drosophila melanogaster and rodent models.

Extracellular acidification occurs in flies during ageing and correlates with mortality rate, independently of strain, sex and diet. With age, flies also become more susceptible to die from acidotic stress, which can be prevented by alkalotic treatment. Acidification is caused by insufficient acid excretion, linked to downregulation of genes in the fly excretory tract that control pH and ATP production, essential for active secretion initiation.