Presynaptic calcium transients evoked by paired-pulse stimulation in the hippocampal slice.
The fluorescent dye Calcium Green and optical recording techniques were used to record intracellular Ca2+ transients resulting from paired-pulse stimulation in stratum moleculare of area CA1 in guinea-pig hippocampal slices. Presumed presynaptic calcium transients were recorded while glutamatergic synaptic transmission was blocked by kynurenic acid. Peak responses to paired-pulses (10-160 ms interval) were higher than responses to single pulses of same stimulation strength (42-23% increase). The isolated response to the second pulse, however, was of smaller magnitude in comparison to the first one; the difference in magnitude depended on the interstimulus interval. Thus, the residual presynaptic free calcium concentration may be responsible for paired-pulse facilitation of synaptic transmission in hippocampus. At the same time, a use-dependent inactivation of presynaptic calcium channels may occur.
Hess
G
G
Department of Neurobiology, Max-Planck-Institute Biophysical Chemistry, Göttingen, Germany.
Kuhnt
U
U
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D004558:Electric Stimulation; D005456:Fluorescent Dyes; D006168:Guinea Pigs; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D007700:Kinetics; D007736:Kynurenic Acid / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology; D011712:Pyramidal Tracts / Q000187:drug effects / Q000502:physiology; D011726:Pyridinium Compounds; D013569:Synapses / Q000187:drug effects / Q000502:physiology*
D005456:Fluorescent Dyes; D011726:Pyridinium Compounds; C050019:1-(3-sulfonatopropyl)-4-(beta)(2-(di-n-butylamino)-6-naphthylvinyl)pyridinium betaine; D007736:Kynurenic Acid; D008274:Magnesium; D002118:Calcium