Arruda J A, Sabatini S, Mola R, Dytko G
J Lab Clin Med. 1980 Sep;96(3):450-9.
In order to investigate a possible role of the microtubules in urinary acidification we measured H+ secretion by the turtle bladder in vitro before and after addition of either colchicine or vinblastine to the serosal phase. Both colchicine and vinblastine inhibited H+ secretion in a dose-dependent fashion; in the control hemibladders H+ secretion remained unchanged. The half-maximal inhibition of H+ secretion occurred at 5.2 x 10(-5) M for colchicine and 7.2 x 10(-6)M for vinblastine. The inhibitory effect of colchicine and vinblastine on H+ secretion was maximal at 10(-4)M and 5 x 10(-4)M, respectively. At these concentrations these compounds failed to alter SCC and resistance. The inhibition of H+ secretion by colchicine or vinblastine increased with time of exposure to the drugs. The effect of colchicine or vinblastine on H+ secretion was not reversible with removal of the drug or with addition of 5% CO2 in the serosal phase. Lumicolchicine, an isomer of colchicine devoid of capacity to interact with microtubules, failed to alter the rate of H+ secretion, suggesting that the observed effect of colchicine on H+ secretion was the result of disruption of microtubule function and not the consequence of nonspecific effect of the drug. These data provide evidence for a role of microtubules in urinary acidification by the turtle bladder in vitro, but an effect of these drugs on membrane-bound tubulin cannot be excluded.
为了研究微管在尿酸化过程中可能发挥的作用，我们在向浆膜侧添加秋水仙碱或长春花碱之前和之后，体外测量了乌龟膀胱的H⁺分泌情况。秋水仙碱和长春花碱均以剂量依赖性方式抑制H⁺分泌；在对照半膀胱中，H⁺分泌保持不变。秋水仙碱对H⁺分泌的半数最大抑制浓度为5.2×10⁻⁵M，长春花碱为7.2×10⁻⁶M。秋水仙碱和长春花碱对H⁺分泌的抑制作用分别在10⁻⁴M和5×10⁻⁴M时达到最大。在这些浓度下，这些化合物未能改变短路电流（SCC）和电阻。秋水仙碱或长春花碱对H⁺分泌的抑制作用随药物暴露时间的延长而增加。去除药物或在浆膜侧添加5%二氧化碳后秋水仙碱或长春花碱对H⁺分泌的作用均不可逆。光秋水仙碱是秋水仙碱的一种异构体，没有与微管相互作用的能力，它未能改变H⁺分泌速率，这表明观察到的秋水仙碱对H⁺分泌的作用是微管功能破坏的结果，而不是药物非特异性作用的后果。这些数据为微管在体外乌龟膀胱尿酸化过程中的作用提供了证据，但不能排除这些药物对膜结合微管蛋白的影响。
