title: Inhibition of 45Ca movements by lowered temperature or lanthanum in rat brain slices.
abstract: Different components of 45Ca movements in rat cortex, striatum and hypothalamus slices were delineated by conditions and ions which selectively alter Ca2+ uptake, binding or extrusion. Equilibration of 45Ca was qualitatively similar in all three tissues and was attained within 30--60 min. The 45Ca tissue-medium ratios obtained in 1.5 mM Ca2+ solutions were increased 15--30% in 0.1 mM Ca2+ solutions and doubled in 0-Ca solutions. Efflux of 45Ca from slices can be described in terms of two components. Lowering the temperature to 0 degree C increased 45Ca uptake into the slower washout component and markedly decreased 45Ca efflux. Exposure to 1.5 mM La3+ decreased both 45Ca uptake and efflux. The inhibitory effects of 0 degree C and La3+ on 45Ca efflux were additive. Uptake of 45Ca in slices incubated in 1.5 mM Sr 2+-substituted (0-Ca) solutions was more similar to that in 0-Ca solutions than in 1.5 mM Ca2+ solutions. Thus, Ca2+ distribution is qualitatively similar in slices from different rat brain areas, loss of 45Ca is an energy dependent process which is at least partially coupled to Ca2+ uptake, decreased temperature inhibits Ca2+ extrusion, La3+ impedes uptake and subsequent binding of Ca2+, and Sr2+ does not prevent the major portion of 45Ca uptake at cellular binding sites. Use of 0 degree C and La3+ to inhibit discrete components of Ca2+ fluxes in rat brain area slices provides a basis for investigation of the mechanisms by which other agents can alter Ca2+ distribution in the central nervous system.
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D003080:Cold Temperature; D003864:Depression, Chemical; D007811:Lanthanum / Q000494:pharmacology*; D008297:Male; D051381:Rats
chemical_list: D007811:Lanthanum; D002118:Calcium