VITAMINS

Mechanism of Intestinal Absorption of Vitamin B_6 : (II)STUDIES WITH THE EVERTED SACS OF RAT INTESTINE

Takahiko TSUJI, Ryo-hei YAMADA

Article type: Article
1974 Volume 48 Issue 10-11 Pages 471-476
Published: November 25, 1974
Released on J-STAGE: March 02, 2018

DOIhttps://doi.org/10.20632/vso.48.10-11_471

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The transport of ^3H-pyridoxine (^3H-PIN) across the intestinal wall was studied by the everted sacs of rat small intestine, mainly at an initial ^3H-PIN concentration of 0.3 μM on the mucosal side and zero on the serosal side. When the sacs were incubated at 37℃ for 4h, the serosal concentration of labelled compounds continued to increase throughout the incubation period, but did not reach the mucosal level, whereas in the tissue the labelled compounds were concentratively accumulated. Ten-fold increase of the initial mucosal concentration of ^3H-PIN from 0.3 to 3 μM did not significantly affect the time course of the serosal to mucosal concentration ratio, although the extent of accumulation in the tissue was much lowered. Futheremore, addition of 300 μM 4-deoxypyridoxine to 0.3 μM ^3H-PIN in the initial mucosal solution did not inhibit the transport at all, but rather stimulated it despite the extreme depression of accumulation in the tissue. By lowering the temperature of incubation to 0℃, where a very little uptake by the tissue was observed, the rate of transport across the wall became about 60% of that at 37℃. When 0.3 μM ^3H-PIN was initially present on both sides of the sacs, the serosal concentration decreased considerably during the early period of incubation, and the tissue accumulated the labelled compounds correspondingly more rapidly. These results have suggested that PIN even at a low concentration as 0.3 μM is transported by simple diffusion across the intestinal wall, and the accumulation of the vitamin by the tissue has no positive role in this transport process but rather decreases the B_6 compounds on the serosal side.

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Studies on the Metabolism of Fatty Acid Esters of L-Ascorbic Acid : (VII)STUDIES ON THE INTESTINAL ABSORPTION OF 6-MONO-LAUROYL-ASCORBIC ACID

Choten INAGAKI, Chieko OKITA, Keiko OSATO, Nobuhiko ARAKAWA

Article type: Article
1974 Volume 48 Issue 10-11 Pages 477-480
Published: November 25, 1974
Released on J-STAGE: March 02, 2018

DOIhttps://doi.org/10.20632/vso.48.10-11_477

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The intestinal absorption of 6-O-mono-lauroyl ascorbic acid (6-Lau_1-AsA) was studied in vitro using the intestinal loop of rabbit. In vivo experiments were also carried out in which 6-Lau_1-AsA had been administered orally to rabbit and the ester or its degradation products, lauric and ascorbic acids, appeared in the blood were estimated. 6-Lau_1-AsA was determined gas-liquid chromatographically according to the method described in our previous report. Available evidence obtained from both in vitro and in vivo experiments suggested that 6-Lau_1-AsA is hydrolyzed into ascorbic and lauric acids before absorbed by the intestine. 6-Lau_1-AsA itself may be impermeable through the intestine.

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Studies on the Oxidative Catalytic Activity of Vitamin B_<12> : (II)0XIDATIVE DECARBOXYLATION OF FORMIC ACID BY VITAMII

Isamu UTSUMI, Kiyoshi HARADA, Hiroshi MIURA

Article type: Article
1974 Volume 48 Issue 10-11 Pages 481-486
Published: November 25, 1974
Released on J-STAGE: March 02, 2018

DOIhttps://doi.org/10.20632/vso.48.10-11_481

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The mechanism of the reaction between formic acid and aquocobalamin (OH-B_<12>) was investigated. When formic acid and OH-B_<12> were incubated in acetate buffer (pH 5) under aerobic conditions at 37℃, carbon dioxide evolution accompanied by oxygen consumption was observed. It was found that 1 mole of OH-B_<12> decarboxylated 20 moles of formic acid. The result of spectrophotometric observation indicated that reduced cobalamin, B_<12r>, is formed as catalytic intermediate in the decarboxylation of formic acid. From these results, it was confirmed that the oxidative decarboxylation of formic acid was catalyzed by traces of OH-B_<12>. The catalytic activity of cobalamin analogs decreased in the order of OH-B_<12>>hydroxocobinamide>DBCC, cyanocobalamin, cyanocobinamide. The mechanism of the catalytic reaction was discussed.

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Pharmacological Studies on Riboflavin Derivatives : (VI)MODE OF PHARMACOLOGICAL ACTION OF 2', 3'-DI-O-NICOTINOYL RIBOFLAVIN-4'(5')-PHOSPHATE

Teruo SAITO, Kentaro KOGI, Hikaru OZAWA

Article type: Article
1974 Volume 48 Issue 10-11 Pages 487-494
Published: November 25, 1974
Released on J-STAGE: March 02, 2018

DOIhttps://doi.org/10.20632/vso.48.10-11_487

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A new riboflavin derivative, 2', 3'-di-o-nicotinoyl riboflavin-4'(5')-phosphate (DNRP) had the constrictory effect on renal artery and the dilatory effect on other arteries as described in the previous paper. In this study, following four experiments were employed to determine the pharmacological correlation among DNRP, dipyridamole (Dip) and adenosine (Ade). (1)The isolated guinea-pig uterus was not contracted by Dip, but was done by DNRP and Ade. Both DNRP and Ade induced contractions in isolated guinea-pig uterus, which being antagonized by aminophylline (Ami). Ade-induced contraction of the uterus was enhanced by Dip, unaffected by DNRP. (2)The contractile response of isolated guinea-pig ileum to transmural electrical stimulation (0.1 cps, 0.6 msec, 50 V) was inhibited by DNRP, Dip and Ade. The inhibitory effect of these three compounds was antagonized by Ami. (3) The effect of Ade on cardiovascular system (the decrease of heart rate, myocardial contractile force and blood pressure) was enhanced by DNRP and Dip in the open-chest dogs. (4) The increase of coronary blood flow induced by either Ade or reactive-hyperemia was enhanced by Dip in dogs, and only the former was enhanced by DNRP. The following suggestion was obtained from these observations, that although DNRP and Dip had enhancing effect on Ade-induced responses, DNRP seemed to have a different mechanism from Dip.

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[title in Japanese]

Dewitt S. Goodman

Article type: Article
1974 Volume 48 Issue 10-11 Pages 495-502
Published: November 25, 1974
Released on J-STAGE: March 02, 2018

DOIhttps://doi.org/10.20632/vso.48.10-11_495

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[title in Japanese]

[in Japanese]

Article type: Article
1974 Volume 48 Issue 10-11 Pages 503-506
Published: November 25, 1974
Released on J-STAGE: March 02, 2018

DOIhttps://doi.org/10.20632/vso.48.10-11_503

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[title in Japanese]

[in Japanese]

Article type: Article
1974 Volume 48 Issue 10-11 Pages 507-511
Published: November 25, 1974
Released on J-STAGE: March 02, 2018

DOIhttps://doi.org/10.20632/vso.48.10-11_507

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[title in Japanese]

[in Japanese]

Article type: Article
1974 Volume 48 Issue 10-11 Pages 513-516
Published: November 25, 1974
Released on J-STAGE: March 02, 2018

DOIhttps://doi.org/10.20632/vso.48.10-11_513

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[title in Japanese]

[in Japanese], [in Japanese]

Article type: Article
1974 Volume 48 Issue 10-11 Pages 517-
Published: November 25, 1974
Released on J-STAGE: March 02, 2018

DOIhttps://doi.org/10.20632/vso.48.10-11_517_1

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[title in Japanese]

[in Japanese]

Article type: Article
1974 Volume 48 Issue 10-11 Pages 517-518
Published: November 25, 1974
Released on J-STAGE: March 02, 2018

DOIhttps://doi.org/10.20632/vso.48.10-11_517_2

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[title in Japanese]

[in Japanese], [in Japanese], [in Japanese]

Article type: Article
1974 Volume 48 Issue 10-11 Pages 518-519
Published: November 25, 1974
Released on J-STAGE: March 02, 2018

DOIhttps://doi.org/10.20632/vso.48.10-11_518

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[title in Japanese]

[in Japanese], [in Japanese], [in Japanese], [in Japanese]

Article type: Article
1974 Volume 48 Issue 10-11 Pages 519-
Published: November 25, 1974
Released on J-STAGE: March 02, 2018

DOIhttps://doi.org/10.20632/vso.48.10-11_519_1

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[title in Japanese]

[in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...

Article type: Article
1974 Volume 48 Issue 10-11 Pages 519-520
Published: November 25, 1974
Released on J-STAGE: March 02, 2018

DOIhttps://doi.org/10.20632/vso.48.10-11_519_2

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[title in Japanese]

[in Japanese], [in Japanese], [in Japanese]

Article type: Article
1974 Volume 48 Issue 10-11 Pages 520-
Published: November 25, 1974
Released on J-STAGE: March 02, 2018

DOIhttps://doi.org/10.20632/vso.48.10-11_520

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