PMC

SARS-CoV-2 viral infection triggers ROS production and oxidative stress in the cell. This viral stress can be attenuated by oxidative preconditioning that induces metabolic changes favoring cell adaptation, repair, and survival. Created by author N. Fath.

Hypoglycemia is a state of energy depletion that leads to metabolic stress. Sympathetic activation leads to symptoms of hypoglycemia awareness and the adrenomedullary response. The normal response to hypoglycemia is a cellular adaptation, assuming the energy depletion and metabolic stress was not enough to induce cell death. The mechanism by which cellular adaptation occurs is unclear but may include the use of alternate fuels (such as lactate) and/or an enhanced glucose transport/phosphorylation/metabolism. During a subsequent hypoglycemic episode, the adapted cell experiences less marked energy depletion and less metabolic stress thus making the cells less susceptible to death. Less intracellular energy depletion leads to impaired sympathetic activation resulting in hypoglycemia unawareness and a reduced adrenomedullary response to subsequent hypoglycemia, collectively known as hypoglycemia associated autonomic failure (HAAF). Preconditioning through recurrent hypoglycemia, paradoxically, acts to render an individual more prone to, but less vulnerable to, an episode of severe hypoglycemia.

Biological effects of remote ischemic preconditioning. Transient ischemia of the arm or leg liberates a circulating effector that induces remote cellular adaptation to a subsequent, extended, and potentially lethal period of ischemia in remote tissues. Reproduced with permission from reference : Kharbanda RK, Nielsen TT, Redington AN. Translation of remote ischaemic preconditioning into clinical practice. Lancet. 2009;374:1557–65.

Potential mechanism of placental adaptation to pregnancy at 3,100 m, as well as the metabolic responses to labor stress based on the results of the current study.