Matching kinetics of synaptic vesicle recycling and enhanced neurotransmitter influx by Ca2+ in brain plasma membrane vesicles.
Using native plasma membrane vesicle suspensions from the rat cerebral cortex under conditions designed to alter intravesicular [Ca2+], we found that Ca2+ induced 47 +/- 5% more influx of [3H]GABA, [3H]D-aspartate and [3H]glycine at 37 degrees C with half-times 1.7 +/- 0.5, 1.3 +/- 0.4 and 1.3 +/- 0.4 min, respectively. We labelled GABA transporter sites with the uptake inhibitor, [3H]-(R,S)-N-[4,4-bis(3-methyl-2-thienyl)but-3-en-1-yl]nipecotic acid and found that Ca2+ induced a partial dissociation of the bound inhibitor from GABA transporter sites with a similar half-time. By means of rapid kinetic techniques applied to native plasma membrane vesicle suspensions, containing synaptic vesicles stained with the amphipathic fluorescent styryl membrane probe N-(3-triethylammoniumpropyl)-4-[4-(dibutylamino)styryl]pyrid inium dibromide, we have measured the progress of the release and reuptake of synaptic vesicles in response to Ca2+ and high-[K+] depolarization in the 0.0004-100 s range of time. Synaptic vesicle exocytosis, strongly influenced by external [Ca2+], appeared with the kinetics accelerated by depolarization. These results are consistent with the potential involvement of Ca2+ in taking low-affinity transporters to the plasma membrane surface via exocytosis.
Kovács
I
I
Institute of Chemistry, Chemical Research Center, Hungarian Academy of Sciences, Budapest.
Szárics
E
E
Nyitrai
G
G
Blandl
T
T
Kardos
J
J
D000818:Animals; D001692:Biological Transport; D001921:Brain / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D005089:Exocytosis; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry; D007700:Kinetics; D008297:Male; D018377:Neurotransmitter Agents / Q000378:metabolism*; D009557:Nipecotic Acids / Q000737:chemistry; D011485:Protein Binding; D011726:Pyridinium Compounds / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar; D013572:Synaptic Vesicles / Q000378:metabolism*; D000078308:Tiagabine
C073804:FM1 43; D005456:Fluorescent Dyes; D018377:Neurotransmitter Agents; D009557:Nipecotic Acids; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds; D002118:Calcium; D000078308:Tiagabine