Calcium-dependent changes of paired-pulse modulation at single GABAergic synapses.
Whole-cell patch-clamp and local electrical stimulation were used for measuring of monosynaptic GABAergic currents from rat hippocampal neurons in culture. Under control conditions (normal extracellular calcium, 2 mM) paired-pulse depression with 150 ms interpulse interval was observed. The mean current amplitude for both 1st and 2nd IPSCs displayed bell-shaped dependency from the stimulus amplitude. When extracellular Ca was either decreased to 0.5 mM or increased to 5 mM both mean amplitude of IPSCs and mean release probability decreased/increased correspondingly yet their dependences from the stimulus strength remained bell-shaped. Mean paired-pulse ratio was also affected--we observed facilitation of second IPSC in low-calcium whereas the latter was depressed in high-calcium solution. Our results suggest that calcium concentrations not only regulate the strength of paired-pulse plasticity but also can invert its direction.
Kravchenko
Mykola O
MO
Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, 4, Bogomoletz str., 01024 Kiev, Ukraine.
Moskalyuk
Anastasia O
AO
Fedulova
Svetlana A
SA
Veselovsky
Nikolay S
NS
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000502:physiology; D006624:Hippocampus / Q000378:metabolism; D009473:Neuronal Plasticity / Q000502:physiology*; D009474:Neurons / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D051381:Rats; D013569:Synapses / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D005680:gamma-Aminobutyric Acid; D002118:Calcium