Acidosis of hippocampal neurones mediated by a plasmalemmal Ca2+/H+ pump.
Modulation of cytosolic calcium ([Ca2+]i) plays a key role in intracellular signalling. In neurones, intracellular Ca2+ transients are involved in the regulation of excitability as well as in synaptic transmission and plasticity. Here, we report that depolarization-induced elevation of [Ca2+]i evokes a prominent fall of intracellular pH (pHi) in voltage-clamped hippocampal pyramidal neurones dialysed with fluorescent indicators of H+ and Ca2+. This acidification is caused by exchange of internal calcium for extracellular protons via a vanadate- and eosin-sensitive plasmalemmal Ca2+/H+ pump. In view of the potent neuromodulatory actions of H+, these results raise the possibility that changes in excitability and synaptic plasticity, hitherto solely attributed to Ca2+ transients, may include a significant component mediated by pH shifts.
II. Physiologisches Institut, Universität Göttingen, Germany.
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S
Trapp
M
M
Lückermann
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K
Kaila
K
K
Ballanyi
D000138:Acidosis / Q000378:metabolism*; D000818:Animals; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D006624:Hippocampus / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D018408:Patch-Clamp Techniques; D051381:Rats; D014638:Vanadates / Q000494:pharmacology
D014638:Vanadates; D000252:Calcium-Transporting ATPases