Reductions in calcium uptake induced in rat brain synaptosomes by ionizing radiation.
Gamma irradiation (60Co) reduced KCl-stimulated voltage-dependent 45Ca2+ uptake in whole-brain, cortical, and striatal synaptosomes. The time course (3, 10, 30, and 60 s) of calcium uptake by irradiated (3 Gy) and nonirradiated synaptosomes, as well as the effect of KCl (15-65 mM), was measured in whole-brain synaptosomes. The fastest and highest rate of depolarization-dependent calcium uptake occurred at 3 s with 65 mM KCl. Irradiation reduced calcium uptake at all incubation times and KCl concentrations. Bay K 8644 enhancement of KCl-stimulated calcium influx was also reduced by radiation exposure. Nimodipine binding to dihydropyridine (DHP) L-type calcium channel receptors was not altered following radiation exposure. These results demonstrate an inhibitory effect of ionizing radiation on the voltage-sensitive calcium channels in rat brain synaptosomes that are not mediated by DHP receptors.
Kandasamy
S B
SB
Behavioral Sciences Department, Armed Forces Radiobiology Research Institute, Bethesda, Maryland 20889-5145.
Howerton
T C
TC
Hunt
W A
WA
D000818:Animals; D001921:Brain / Q000166:cytology*; D002118:Calcium / Q000493:pharmacokinetics*; D002540:Cerebral Cortex / Q000166:cytology; D003037:Cobalt Radioisotopes; D003342:Corpus Striatum / Q000166:cytology; D066298:In Vitro Techniques; D008297:Male; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013268:Stimulation, Chemical; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects*; D013997:Time Factors
D003037:Cobalt Radioisotopes; D011189:Potassium Chloride; D002118:Calcium