Effect of nicotinamide-adenine dinucleotides on Ca2+ transport system in rat liver nuclei: stimulation of Ca2+ release by NAD+.
The effect of nicotinamide-adenine dinucleotides (NAD+ and NADP+) on Ca2+ transport in rat liver nuclei was investigated. Ca2+ uptake and release were determined with a Ca2+ electrode. Ca2+ uptake was dependent on adenosine triphosphate (ATP; 2 mM). The presence of NAD+ (2 mM) or NADP+ (1 and 2 mM) caused a significant inhibition of Ca2+ uptake following addition of 2 mM ATP. Ca2+, which accumulated in the nuclei during 6 min after ATP addition, was significantly released by the addition of NAD+ (0.5-2 mM) or NADP+ (0.1-2 mM). However, the effect of NADH (2 mM) or NADPH (2 mM) on Ca2+ uptake and release clearly weakened in comparison with the effects of NAD+ and NADP+. Meanwhile, ryanodine (10 microM), thapsigargin (10 microM) or oxalate (0.5 mM) had no effect on Ca2+ uptake and release in rat liver nuclei. These reagents did not significantly alter the effects of 2 mM NAD+ on Ca2+ uptake and release. Thus, NAD+ and NADP+ had a potent effect on Ca2+ transport in rat liver nuclei. The present findings suggest that the liver cytosolic NAD+ (NADP+) is a factor in the regulation of the nuclear Ca2+ concentration.
Oishi
K
K
Laboratory of Metabolism and Endocrinology, Graduate School of Nutritional Sciences, University of Shizuoka, Japan.
Yamaguchi
M
M
D000818:Animals; D001692:Biological Transport / Q000502:physiology; D002118:Calcium / Q000378:metabolism*; D002467:Cell Nucleus / Q000187:drug effects* / Q000378:metabolism; D008099:Liver / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D008297:Male; D009243:NAD / Q000494:pharmacology*; D009249:NADP / Q000494:pharmacology*; D010070:Oxalates / Q000494:pharmacology; D019815:Oxalic Acid; D051381:Rats; D017208:Rats, Wistar; D012433:Ryanodine / Q000494:pharmacology; D013729:Terpenes / Q000494:pharmacology; D019284:Thapsigargin
D010070:Oxalates; D013729:Terpenes; D009243:NAD; D012433:Ryanodine; D009249:NADP; D019284:Thapsigargin; D019815:Oxalic Acid; D002118:Calcium