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Type: Artigo de periódico
Title: Calcium Transport By Corn Mitochondria : Evaluation Of The Role Of Phosphate.
Author: Silva, M A
Carnieri, E G
Vercesi, A E
Abstract: Mitochondria from some plant tissues possess the ability to take up Ca(2+) by a phosphate-dependent mechanism associated with a decrease in membrane potential, H(+) extrusion, and increase in the rate of respiration (AE Vercesi, L Pereira da Silva, IS Martins, CF Bernardes, EGS Carnieri, MM Fagian [1989] In G Fiskum, ed, Cell Calcium Metabolism. Plenum Press, New York, pp 103-111). The present study reexamined the nature of the phosphate requirement in this process. The main observations are: (a) Respiration-coupled Ca(2+) uptake by isolated corn (Zea mays var Maya Normal) mitochondria or carbonyl cyanide p-trifluoromethoxyphenylhydrazone-induced efflux of the cation from such mitochondria are sensitive to mersalyl and cannot be dissociated from the silmultaneous movement of phosphate in the same direction. (b) Ruthenium red-induced efflux is not affected by mersalyl and can occur in the absence of phosphate movement. (c) In Ca(2+)-loaded corn mitochondria, mersalyl causes net Ca(2+) release unrelated to a decrease in membrane potential, probably due to an inhibition of Ca(2+) cycling at the level of the influx pathway. It is concluded that corn mitochondria (and probably other plant mitochondria) do possess an electrophoretic influx pathway that appears to be a mersalyl-sensitive Ca(2+)/inorganic phosphate-symporter and a phosphate-independent efflux pathway possibly similar to the Na(2+)-independent Ca(2+) efflux mechanism of vertebrate mitochondria, because it is not stimulated by Na(+).
Rights: fechado
Identifier DOI: 
Date Issue: 1992
Appears in Collections:Artigos e Materiais de Revistas Científicas - Unicamp

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