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Volume 84, Issue 12
Displaying 1-7 of 7 articles from this issue
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[in Japanese]Article type: Article
2010 Volume 84 Issue 12 Pages 573-576
Published: December 25, 2010
Released on J-STAGE: October 10, 2017
JOURNAL FREE ACCESSDownload PDF (455K) -
Akiko OhashiArticle type: Article
2010 Volume 84 Issue 12 Pages 577-588
Published: December 25, 2010
Released on J-STAGE: October 10, 2017
JOURNAL FREE ACCESSTetrahydrobiopterin (BH_4), an endogenous active compound, plays a crucial role in the biosynthesis of aromatic monoamines and nitric oxide as well as the conversion of phenylalanine to tyrosine. BH_4 deficiency causes extensive dysfunction of the body systems including the nervous and cardiovascular systems. Supplementation of BH_4 has not prevailed despite its potential effectiveness against BH_4 deficiency. The level of BH_4 in the body is maintained by keeping a balance between its de novo synthesis and urinary excretion. The urinary excretion of BH_4 is attenuated by its reabsorption at the renal tubules under ordinary conditions. Orally administered BH_4 is absorbed very efficiently, and subsequently a large increase in blood BH_4 concentration occurs. However, the increase in blood BH_4 concentration provokes its active secretion across the renal epithelial cells as well as glomerular filtration, resulting in a decrease in the increased blood level of BH_4 to its ordinary level. In this review, we discuss both the roles of BH_4 as a coenzyme, and the intestinal absorption, tissue distribution and urinary excretion.View full abstractDownload PDF (2023K) -
Kaeko Murota, Yoshichika Kawai, Junji TeraoArticle type: Article
2010 Volume 84 Issue 12 Pages 589-598
Published: December 25, 2010
Released on J-STAGE: October 10, 2017
JOURNAL FREE ACCESSFlavonoids are present in various plant foods such as vegetables, fruits and beverages. Flavonoids are known as powerful antioxidants and have attracted much attention to their potential role in the prevention of various diseases. In plant foods, most flavonoids exist as glycosides and/or acidic forms, and the type of a sugar moiety is a major determinant of the intestinal absorption. In the gastrointestinal tract, dietary flavonoids are mainly absorbed as their aglycone forms by simple diffusion, whereas there are some kind of membrane transporters that may work for cellular influx of certain flavonoids. The predominant circulating molecules after an oral consumption are conjugative metabolites because flavonoids undergo extensive intestinal and hepatic glucuronidation and sulfation. ABC transporters have been shown to serve for the cellular efflux of flavonoid metabolites. This review will summarize the current literatures regarding on the transport mechanism of dietary flavonoids and their conjugative metabolites.View full abstractDownload PDF (1361K) -
Naohiko AnzaiArticle type: Article
2010 Volume 84 Issue 12 Pages 599-603
Published: December 25, 2010
Released on J-STAGE: October 10, 2017
JOURNAL FREE ACCESSProstaglandins (PGs) are one kind of the autacoids derived from cyclooxygenase-initiated arachidonic acid metabolism, which exert effects by interacting with their specific G protein-coupled receptors in the vicinity of their production. Similar to the neurotransmission in synapse, released PGs should be removed rapidly from extracellular space to terminate its signaling. It is known that PG inactivation is involved in active uptake into the cell followed by cytoplasmic oxidation. PGs are charged organic anions at physiological pH. Therefore, a carrier-mediated membrane transport for PGs was hypothesized. In 1995, the group of Schuster identified the first prostaglandin transporter PGT, leading to the accumulation of information concerning individual molecules involved in membrane permeation of PGs such as SLC22 organic anion transporters (OATs), multidrug resistance protein MRP4, and organic solute transporter OSTα-OSTβ. Recent advances in research on the membrane transport of PGs are reviewed in this paper.View full abstractDownload PDF (741K) -
Yoshimichi SaiArticle type: Article
2010 Volume 84 Issue 12 Pages 604-609
Published: December 25, 2010
Released on J-STAGE: October 10, 2017
JOURNAL FREE ACCESSL-Carnitine (β-hydroxyl-γ-trimethylaminobutyric acid) acts as an essential cofactor for β-oxidation of long-chain fatty acids by facilitating the transport of fatty acid across the inner membranes of mitochondria as acylcarnitine esters. OCTN2 (SLC22A5) was first isolated as a novel organic cation transporter with high homology to OCTN1 (SLC22A4). OCTN2 has a high affinity for carnitine and acylcarnitine and efficiently transports them in Na^+-dependent manner. Mutation of OCTN2 leads to primary systemic carntine deficiency (SCD; OMIM 212140). SCD is an autosomal recessive disorder characterized by progressive cardiomyopathy, skeletal myopathy, hypoglycemia and hyperammonaemia. Several pharmacokinetic studies using a SCD model mouse, jvs (juvenile visceral steatosis), have revealed that OCTN2 governs carntine disposition in vivo. OCTN2 is involved in the efficient reabsorption of carntine in renal tubular epithelial cells. OCTN2 also function as the uptake transporter in the intestine, the heart, the liver and male reproduction system.View full abstractDownload PDF (877K) -
Shigeo KureArticle type: Article
2010 Volume 84 Issue 12 Pages 610-611
Published: December 25, 2010
Released on J-STAGE: October 10, 2017
JOURNAL FREE ACCESSDownload PDF (393K) -
Keisuke Nakashima, Tomohiro YanoArticle type: Article
2010 Volume 84 Issue 12 Pages 612-
Published: December 25, 2010
Released on J-STAGE: October 10, 2017
JOURNAL FREE ACCESSDownload PDF (199K)
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