胆囊收缩素及其他促分泌素对胰腺α-氨基异丁酸摄取的抑制作用。

Inhibition of pancreatic alpha-aminoisobutyric acid uptake by cholecystokinin and other secretagogues.

作者信息

Iwamoto Y, Williams J A

出版信息

Am J Physiol. 1980 May;238(5):G440-4. doi: 10.1152/ajpgi.1980.238.5.G440.

DOI:10.1152/ajpgi.1980.238.5.G440

Abstract

The uptake of the non-metabolizable amino acid, alpha-aminoisobutyric acid (AIB), by isolated mouse pancreatic acini was studied. AIB was concentrated in acinar cell water by an Na+-dependent mechanism. The protein hormone secretagogues caerulein, cholecystokinin, and gastrin and the cholinergic agent carbachol inhibited AIB uptake by greater than 50% of control. The effect of secretagogues on AIB uptake was maximal at hormone concentrations that are slightly higher than those that are maximal for amylase release, but comparable to those concentrations that maximally increase glucose transport by acini. This inhibition of AIB uptake was mediated by both inhibition of AIB influx and stimulation of AIB efflux. In the presence of Ca2+, the Ca2+ ionophore A23187 mimicked the effect of caerulein on AIB uptake. In the absence of Ca2+, control AIB uptake was markedly decreased and both caerulein and A23187 had no further effects. It was concluded, therefore, that secretagogues known to induce enzyme release by an effect on cellular Ca2+ also decrease AIB uptake and that this effect on uptake is most likely mediated by Ca2+.

摘要

研究了分离的小鼠胰腺腺泡对不可代谢氨基酸α-氨基异丁酸（AIB）的摄取情况。AIB通过一种依赖于Na⁺的机制在腺泡细胞内液中被浓缩。蛋白质类激素促分泌剂蛙皮素、胆囊收缩素和胃泌素以及胆碱能药物卡巴胆碱抑制AIB摄取，抑制程度超过对照的50%。促分泌剂对AIB摄取的作用在激素浓度略高于淀粉酶释放最大值时达到最大，但与使腺泡葡萄糖转运最大化增加的浓度相当。这种对AIB摄取的抑制是通过抑制AIB内流和刺激AIB外流介导的。在有Ca²⁺存在的情况下，Ca²⁺离子载体A23187模拟了蛙皮素对AIB摄取的作用。在无Ca²⁺的情况下，对照的AIB摄取明显减少，蛙皮素和A23187均无进一步作用。因此得出结论，已知通过影响细胞Ca²⁺诱导酶释放的促分泌剂也会降低AIB摄取，并且这种对摄取的作用很可能由Ca²⁺介导。