Mammal Brains, Calcium And Oxygen Deprivation
Infant mammals, including humans, are known to be much more tolerant of oxygen deprivation than older juveniles or adults. It turns out that calcium is a key factor in this tolerance. Normally, calcium ions in our brain cells play vital roles, including helping memories form. But it’s a delicate balance: small amounts of calcium are essential for brain function, but too much calcium makes things go haywire. When nerve cells are starved of oxygen, they no longer have the energy to regulate calcium entry, resulting in an influx of too much calcium, which poisons the cells. This is the primary cause of neuronal death during oxygen deprivation.
In the last decade or so, researchers discovered that adult and infant brains express different calcium channels in their cell membranes. Calcium channels in infants actually close during oxygen deprivation, protecting the brain cells from calcium overdose in the womb, where the baby gets much less oxygen. After the baby is born, however, oxygen is plentiful, and these channels are largely replaced by ones that open in response to oxygen deprivation, often leading to cell death.
Quoted on Fri Jun 29th, 2012