Regulatory effect of arachidonic acid on the calcium transport system in rat liver nuclei.
The effect of arachidonic acid (AA) on Ca2+ transport in rat liver nuclei was investigated. Ca2+ uptake and release were determined with a Ca2+ electrode. Ca2+ uptake increased dependent on ATP (0.5-2.0 mM), while uptake was negligible in the presence of 2.0 mM ADP or AMP. AA (10-100 microM) caused a marked inhibition of Ca2+ uptake following the addition of 2.0 mM ATP. Also, Ca2+, which accumulated in the nuclei during 6 min after ATP addition, was clearly released by the addition of AA (10-100 microM). The alterations were concentration dependent. The nuclear Ca2+ uptake and release were not altered significantly by the presence of prostaglandin E2 (10 and 20 microM), prostaglandin H2 (1 and 4 microM), thromboxane B2 (1 and 4 microM), leukotriene A4 (1 and 4 microM), Ins(1,4,5)P3 (1 and 10 microM) or dibutyryl cAMP (10 and 50 microM). Only, 5-hydroxy-eicosatetraenoic acid (5-HETE) at 4 microM caused a significant inhibition of nuclear Ca2+ uptake and an appreciable increase in Ca2+ release; the 1 microM concentration had no effect. These results indicate that AA, one of the prostanoids, has a unique effect on Ca2+ uptake and release in rat liver nuclei. The finding suggests that AA has a regulatory effect on the Ca2+ transport system in liver nuclei.
Laboratory of Metabolism and Endocrinology, Graduate School of Nutritional Sciences, University of Shizuoka, Japan.
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Oishi
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Yamaguchi
D000818:Animals; D016718:Arachidonic Acid / Q000494:pharmacology*; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D004229:Dithiothreitol / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D006893:Hydroxyeicosatetraenoic Acids / Q000494:pharmacology; D017572:Leukotriene A4; D015289:Leukotrienes / Q000494:pharmacology; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D011453:Prostaglandins / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013929:Thromboxane B2 / Q000494:pharmacology
D006893:Hydroxyeicosatetraenoic Acids; D017572:Leukotriene A4; D015289:Leukotrienes; D011453:Prostaglandins; D016718:Arachidonic Acid; C022022:5-hydroxy-6,8,11,14-eicosatetraenoic acid; D013929:Thromboxane B2; D002118:Calcium; D004229:Dithiothreitol