In situ ileal absorption of insulin in rats:: Effects of hyaluronidase pretreatment diminishing the mucous/glycocalyx layers
In situ ileal absorption of insulin in rats:: Effects of hyaluronidase pretreatment diminishing the mucous/glycocalyx layers
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DOI：
10.1023/b:pham.0000016244.88820.28
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发表时间：
2004-02-01
影响因子：
3.7
通讯作者：
Takayama, K
中科院分区：
文献类型：
--
作者：
Morishita, M;Aoki, Y;Takayama, K
目的。检验回肠粘液层/糖帽层可以被透明质酸酶去除的假设，从而确定它们在胰岛素吸收中的重要作用。用不同浓度的透明质酸酶“灌流”或“暴露”处理大鼠回肠段，在原位回肠循环系统中研究胰岛素和4.4、20、40 kDa异硫氰酸荧光素标记的右旋糖苷(FDs)的吸收。透射电子显微镜观察透明质酸酶处理后粘液/糖帽层的减少，光镜观察细胞内和细胞间的完整性和/或损伤，乳酸脱氢酶(LDH)渗漏和膜电阻(R-m)。透明质酸酶“灌流”浓度大于或等于160U/ml的预处理30分钟可显著增加原位注射50IU/kg胰岛素后的降糖反应。这种增强作用依赖于透明质酸酶的浓度和“暴露”时间，并伴随着透明质酸酶预处理后粘液/糖萼层减少的透射电子显微镜观察，但造成了不可检测的组织损伤。相比之下，透明质酸酶对FDs的吸收、LDH漏出量和R-m值无明显影响，提示各层对弥散吸收的作用不明显。透明质酸酶预处理可增加回肠对胰岛素的吸收，但不会增加FDs的吸收，这是由于粘液/糖帽层减少，而不会造成可检测到的细胞损伤。
Purpose. To test the hypothesis that the ileal mucous/glycocalyx layers can be removed by hyaluronidase and that their significant roles in insulin absorption can thereby be identified.Methods. Rat ileal segments were pretreated with various concentrations of hyaluronidase by "perfusion" or "exposure", and the absorption of insulin and 4.4-, 20-, and 40-kDa fluorescein isothiocyanate-labeled dextrans (FDs) were studied in the in situ ileal loop system. Diminished mucous/glycocalyx layers following the hyaluronidase pretreatment was confirmed by transmission electron microscopy (TEM), whereas intra- and intercellular integrity and/or damage was examined by light microscopy, lactate dehydrogenase (LDH) leakage, and membrane electrical resistance (R-m).Results. Hyaluronidase "perfusion" pretreatment at concentrations greater than or equal to160 U/ml for 30 min significantly increased the hypoglycemic responses following in situ administration of insulin at 50 IU/kg. This enhancing effect was found to be dependent on hyaluronidase concentration and "exposure" periods and accompanied by the TEM observation of diminished mucous/glycocalyx layers from the hyaluronidase pretreatment, yet causing undetectable histological damage. In contrast, the absorption of FDs and the values for LDH leakage and R-m were unaffected by the hyaluronidase pretreatment, suggesting that the layers functioned insignificantly to diffusive absorption.Conclusions. Hyaluronidase pretreatment increased ileal absorption of insulin, but not FDs, by virtue of the diminished mucous/glycocalyx layers without causing detectable cellular damage.