Mechanisms by which protons increase [Ca2+]
. A) Ca2+ imaging showing acidosis-induced [Ca2+i increase in dendrites and dendritic spines. Organotypic hippocampal slices were transfected with cameleon and stimulated with a pH 6.0 solution. Left image shows the overview of the imaged dendritic segment. Right ratiometric images show YFP/CFP ratio (red indicates high while blue indicates low Ca2+) before and during acidic stimulation. Note the increase in Ca2+ in the dendrite and most dendritic spines. Data adapted from. B) Drawing showing how protons lead to [Ca2+i increase in neurons. See text for detailed explanation. Depending on the magnitude and duration of the Ca2+ rise, acidosis can alter neural plasticity or, when [Ca2+i passes certain threshold level, lead to neuronal injury.