Schwartz S E, Stauffer J Q, Burgess L W, Cheney M
Biochim Biophys Acta. 1980 Mar 13;596(3):404-13. doi: 10.1016/0005-2736(80)90127-3.
Hyperoxaluria is a complication of disorders associated with steatorrhea. The colon is the presumed site of enhanced oxalate absorption in patients with steatorrhea. We performed studies of colonic mucosal oxalate uptake in everted sacs of rat colon to determine the kinetics of colonic oxalate transport and to evaluate the effect of both pH and ricinoleic acid, a hydroxy fatty acid, on colonic oxalate uptake. Our study demonstrated that oxalate is transported throughout the colon by passive diffusion. Tissue uptake increased linearly with increasing oxalate concentrations and was unaffected by metabolic inhibitors, oxygen deprivation, or temperature changes. There were pH-dependent regional differences of oxalate uptake both in the presence and absence of ricinoleic acid. In the absence of ricinoleic acid, the highest oxalate uptake occurred at the lower pH values (5.4 and 6.4). In the presence of ricinoleic acid oxalate uptake was enhanced at the higher pH values (7.4 and 8.4); a finding most likely related to decreased solubility of ricinoleic acid at pH 5.4 and 6.4. Intraluminal pH is an important determinant of colonic oxalate uptake in the presence and absence of ricinoleic acid.
高草酸尿症是与脂肪泻相关疾病的一种并发症。结肠被认为是脂肪泻患者草酸盐吸收增强的部位。我们对大鼠结肠外翻囊的结肠黏膜草酸盐摄取进行了研究，以确定结肠草酸盐转运的动力学，并评估pH值和蓖麻油酸（一种羟基脂肪酸）对结肠草酸盐摄取的影响。我们的研究表明，草酸盐通过被动扩散在整个结肠中转运。组织摄取量随草酸盐浓度增加呈线性增加，且不受代谢抑制剂、缺氧或温度变化的影响。在有和没有蓖麻油酸的情况下，草酸盐摄取均存在pH依赖性区域差异。在没有蓖麻油酸的情况下，草酸盐摄取量在较低pH值（5.4和6.4）时最高。在有蓖麻油酸的情况下，草酸盐摄取在较高pH值（7.4和8.4）时增强；这一发现很可能与蓖麻油酸在pH 5.4和6.4时溶解度降低有关。管腔内pH值是有和没有蓖麻油酸时结肠草酸盐摄取的重要决定因素。
