Adenosine release is a major cause of failure of synaptic transmission during hypoglycaemia in rat hippocampal slices.
Glucose-free medium (aglycaemia) caused a complete failure of CA1 population spikes (after 14.5 +/- 0.8 min) and field EPSPs (after 18.1 +/- 0.5 min). In the presence of the selective adenosine A1 antagonist, 8-(p-sulfophenyl)theophylline (10 microM), population spikes and EPSPs were decreased by only 13.8 +/- 11.9% and 32.4 +/- 11.6% at the end of 17.0 +/- 3.0 min and 19.8 +/- 1.7 min of aglycaemia, respectively. A similar effect was produced by caffeine (0.2 mM). The ATP-sensitive K+ channel blockers tolbutamide (1 mM) and glibenclamide (10 microM) had no significant effect on aglycaemic suppression of synaptic transmission. These observations indicate that endogenous adenosine, but not ATP-sensitive K+ conductance, plays a major role in hypoglycaemia failure of transmission.
Anaesthesia Research Department, McGill University, Montréal, Que, Canada.
P J
PJ
Zhu
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K
Krnjević
D000200:Action Potentials / Q000187:drug effects; D000241:Adenosine / Q000378:metabolism*; D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D015687:Cell Hypoxia; D004734:Energy Metabolism; D005071:Evoked Potentials / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology; D005905:Glyburide / Q000494:pharmacology; D006624:Hippocampus / Q000378:metabolism*; D007003:Hypoglycemia / Q000378:metabolism / Q000503:physiopathology*; D009433:Neural Inhibition; D011188:Potassium / Q000502:physiology; D015221:Potassium Channels / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D009435:Synaptic Transmission / Q000187:drug effects*; D013806:Theophylline / Q000031:analogs & derivatives / Q000494:pharmacology; D014044:Tolbutamide / Q000494:pharmacology
D015221:Potassium Channels; D002110:Caffeine; C031433:8-(4-sulfophenyl)theophylline; D014044:Tolbutamide; D013806:Theophylline; D005947:Glucose; D000241:Adenosine; D011188:Potassium; D005905:Glyburide