title: Regulation of the mitochondrial ATP-Mg/Pi carrier in isolated hepatocytes.
abstract: This study investigated the cellular regulation of net adenine nucleotide movements between the cytoplasm and mitochondria in intact cells. Such movements are presumed to occur primarily by ATP-Mg exchange with Pi via the mitochondrial ATP-Mg/Pi carrier. Vasopressin, A23187, and thapsigargin all elevate intracellular free [Ca2+] and all caused dose-dependent increases in the mitochondrial adenine nucleotide content (29, 63, and 39%, respectively). Phorbol 12-myristate 13-acetate had no effect. The effect of vasopressin was abolished when cytoplasmic [ATP] was decreased (by 43%) and [Pi] was increased (3-fold) by addition of carboxyatractyloside. The effect of thapsigargin was abolished by addition of xylulose to deplete cytoplasmic [ATP] (by 50%) and [Pi] (> 4-fold). The results indicate that in intact cells Ca2+ activates the mitochondrial ATP-Mg/Pi carrier to enable changes in the subcellular distribution of adenine nucleotides and that the relative [ATP] and [Pi] gradients govern the direction and magnitude of net adenine nucleotide movements between the cytoplasm and mitochondria.
authors.affiliation: Department of Biology, Tufts University, Medford, Massachusetts 02155.
authors.forename: D T
authors.initials: DT
authors.lastname: Dransfield
authors.forename: J R
authors.initials: JR
authors.lastname: Aprille
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D017920:Antiporters; D001278:Atractyloside / Q000031:analogs & derivatives / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002352:Carrier Proteins / Q000378:metabolism; D002469:Cell Separation; D002478:Cells, Cultured; D003593:Cytoplasm / Q000502:physiology / Q000648:ultrastructure; D004305:Dose-Response Relationship, Drug; D008099:Liver / Q000166:cytology* / Q000502:physiology* / Q000648:ultrastructure; D008297:Male; D008930:Mitochondria, Liver / Q000737:chemistry / Q000502:physiology* / Q000648:ultrastructure; D024101:Mitochondrial Proteins; D010710:Phosphates / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013729:Terpenes / Q000494:pharmacology; D019284:Thapsigargin; D014667:Vasopressins / Q000494:pharmacology
chemical_list: C086357:ATP-Mg-Pi carrier proteins, mitochondria; D017920:Antiporters; D002352:Carrier Proteins; D024101:Mitochondrial Proteins; D010710:Phosphates; D013729:Terpenes; D014667:Vasopressins; D001278:Atractyloside; D000001:Calcimycin; D019284:Thapsigargin; D000255:Adenosine Triphosphate; D000252:Calcium-Transporting ATPases; C003853:carboxyatractyloside