Effects of taurine and mitochondrial metabolic inhibitors on ATP-dependent Ca2+ uptake in synaptosomal and mitochondrial subcellular fractions of rat retina.
ATP-dependent Ca2+ uptake was investigated at low Ca2+ concentrations (10 microM) in rat retinal synaptosomal and mitochondrial preparations obtained by differential centrifugation on Ficoll gradients. Ca2+ uptake in the synaptosomal and mitochondrial subcellular preparations was stimulated by ATP and additionally stimulated by ATP plus taurine. The ATP-dependent and taurine-stimulated ATP-dependent Ca2+ uptakes were inhibited by mitochondrial metabolic inhibitors (atractyloside, oligomycin, and ruthenium red). These metabolic inhibitors had a greater effect on the ATP-dependent and taurine-stimulated ATP-dependent Ca2+ uptake activities in the mitochondrial preparation than in the synaptosomal preparation. ATP-dependent Ca2+ uptake in a synaptosomal subfraction obtained by osmotic shock was only partially inhibited by atractyloside. ATP-dependent Ca2+ uptake in the synaptosomal subfraction was also stimulated by taurine but to a lesser extent than in either the synaptosomal or mitochondrial preparation. These studies suggest that mitochondria are primarily responsible for taurine-stimulated ATP-dependent Ca2+ uptake in synaptosomal preparations.
Lombardini
J B
JB
Department of Pharmacology, Texas Tech University Health Sciences Center, Lubbock 79430.
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D001278:Atractyloside / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D008854:Microscopy, Electron; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D009840:Oligomycins / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012160:Retina / Q000648:ultrastructure*; D012430:Ruthenium Red / Q000494:pharmacology; D013574:Synaptosomes / Q000378:metabolism*; D013654:Taurine / Q000494:pharmacology*
D009840:Oligomycins; D012430:Ruthenium Red; D001278:Atractyloside; D013654:Taurine; D011189:Potassium Chloride; D000255:Adenosine Triphosphate; D002118:Calcium