糖質の膜透過に及ぼすInsulinの効果に関する研究

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Participation of insulin in the transfer of sugars into cells has been confirmed by Levine's experiment demonstrating that the distribution of d-galactose in evicerated animal increases in the presence of insulin. Levine and his colleagues have postulated that only the sugars possessing the same steric configulation as d-glucose at carbons 1, 2 and 3 are aided by insulin to enter muscle tissues. However, the accelerating action of insulin on sugar distribution can be observed more precisely in vitro than in vivo. The present study was undertaken to ascertain Levine's postulate using "intact diaphragm preparations" first described by Kipnis & Cori, and to investigate the relationship of logarithmic doses of insulin with the accelerating effect of insulin on sugar transport. On the other hand, thyroid stimulating hormone (TSH) has been shown to increase the incorporation of amino acid into protein, and ci-aminoisobutyric acid uptake in thyroid tissue in vitro. These effects of TSH were quite similar to those of insulin, therefore, participation of TSH in the transfer of sugars into thyroid was researched in the present study using bovine thyroid slices. And the stereospecificity in the action of insulin was compared with that of TSH. Results : Marked insulin effects were observed on the spaces of d-xylose and 1-arabinose, both belonging to "responsive sugar". The effects of insulin upon the spaces of d-arabinose and 1-xylose, both belonging to "non-responsive sugar", were also significant, although the effects were less marked than those of insulin on "responsive sugar" spaces. There was no significant difference between the effects of insulin upon the "responsive sugar" spaces, and the difference between the effects of insulin upon the 1-xylose, and d-arabinose was statistically significant. In this case, insulin effects on the spaces of d-arabinose were more marked than that of 1-xylose. In short, insulin also stimulated the intracellular distribution of "non-resposive sugar". Namely, responsiveness of those sugars to insulin appeared to be modified by other configulations of the molecule than carbons 1, 2 and 3. The effect of TSH on the distribution of pentoses in thyroid slices were limited to only the spaces of d-xylose and 1-arabinose. "Non-responsive sugar" spaces were not significantly increased in TSH addition. In rat diaphragm, the relationship of logarithmic doses of insulin (X : u./ml.) to id-xylose (insulin effect, Y : mg./g. of wet muscle) appeared to be sigmoid in shape. Rectilinear regression proved to be highly significant in the range of 10-5 to 10-5 u./ml. The equation of regression line was Y-0.47=0.26 (X-3.62). Insulin-like activity of the sera from a patient with hypoglycemic syndrome was estimated as an application of this method, and a diagnosis of insuloma was made, which was ascertained by laparotomy. Summary : 1) In rat diaphragm, insulin stimulates not only the distribution of "responsive sugar" but also that of "non-responsive sugar". The responsiveness of the latter to insulin is less than the former ; in the latter group the response of d-arabinose to insulin is superior to that of l-xylose. The responsiveness of pentoses to insulin follows an order of "responsive sugar" >d-arabinose>l-xylose. 2) In bovine thyroid slice, TSH stimulates the distribution of d-xylose and l-arabinose without any effect on "non-responsive sugar". In the effect of TSH on the distribution of pentoses in thyroid tissue, there seems to be more strict stereospecificity than in the case of insulin. 3) In intact diaphragm, log-dose response curve of insulin proves to be sigmoid in shape. In the range of 10-5 to 10-2 u./ml., rectilinear regression proved to be highly significant.
日本内分泌学会の論文

糖質の膜透過に及ぼすInsulinの効果に関する研究

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