Mechanism of the hippocampal loss of adenosine sensitivity in calcium-free media.
Adenosine depresses the excitability of pyramidal neurones in the hippocampus. This effect is lost in calcium-free media and we have now investigated the mechanism of this. Extracellular recordings were made of antidromically and orthodromically evoked population potentials from CA1 region of rat hippocampal slices. It was observed that the activity of adenosine can be restored in the presence of procaine or carbamazepine, known inhibitors of sodium channels. The GABAB agonist baclofen was able to depress potential size but did not restore sensitivity to adenosine. It is concluded that the loss of postsynaptic sensitivity to adenosine in calcium-free solution results from the increased sodium conductances.
Hosseinzadeh
H
H
Department of Pharmacology, University of Glasgow, UK.
Stone
T W
TW
D000241:Adenosine / Q000494:pharmacology*; D000818:Animals; D001418:Baclofen / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology*; D002220:Carbamazepine / Q000494:pharmacology; D003470:Culture Media; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000187:drug effects; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D008297:Male; D011343:Procaine / Q000494:pharmacology; D017966:Pyramidal Cells / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D013268:Stimulation, Chemical
D003470:Culture Media; D002220:Carbamazepine; D011343:Procaine; D001418:Baclofen; D000241:Adenosine; D002118:Calcium