Stoll R, Ruppin H, Domschke W
Department of Medicine, University of Erlangen-Nuremberg, Federal Republic of Germany.
Gastroenterology. 1988 Jul;95(1):69-76. doi: 10.1016/0016-5085(88)90292-2.
We investigated whether the synthetic opiate loperamide-HCl is able to regulate specific transport systems for sodium and chloride in brush border membrane vesicles (BBMVs) from human ileum and whether such activities are mediated by calcium/calmodulin. In BBMVs we studied Na+/H+ antiport, Cl+/OH- antiport, Na+/Cl- cotransport, and the Cl- conductive pathway. Brush border membrane vesicles were incubated with 10 microM loperamide over 4 h at 5 degrees C before the uptake experiments. In ileal BBMVs, loperamide stimulated intravesicular accumulation of Na+ in the presence of Cl- and vice versa. After 1 min of incubation, the stimulatory effect was 35% +/- 5% (p less than 0.005) of the control without loperamide. Loperamide also stimulated Cl-/OH- antiport by 30% +/- 5% (p less than 0.005) in BBMVs of ileum. In addition, we studied the role of Ca2+/calmodulin in the action of loperamide on chloride transport by human BBMVs. In loperamide-pretreated BBMVs, calmodulin activity was significantly decreased (12 +/- 2 vs. 38 +/- 4 pmol/mg protein). When loperamide-pretreated vesicles were incubated with 2 microM calcium (free concentration) plus 5 microM calmodulin for 1 h at 5 degrees C, complete inhibition of the stimulatory effect of loperamide on Cl-/OH- antiport and Na+/Cl- cotransport was observed. Increasing the Ca2+/calmodulin activity of loperamide-pretreated BBMVs with 2 microM calcium plus 5 microM calmodulin led to a significant inhibition of Cl-/OH- antiport and Na+/Cl- cotransport by 40% +/- 5% (p less than 0.005).
我们研究了合成阿片类药物盐酸洛哌丁胺是否能够调节人回肠刷状缘膜囊泡（BBMVs）中钠和氯的特定转运系统，以及此类活性是否由钙/钙调蛋白介导。在BBMVs中，我们研究了Na⁺/H⁺逆向转运、Cl⁺/OH⁻逆向转运、Na⁺/Cl⁻协同转运以及Cl⁻传导途径。在摄取实验前，将刷状缘膜囊泡与10微摩尔/升洛哌丁胺在5℃下孵育4小时。在回肠BBMVs中，洛哌丁胺在有Cl⁻存在的情况下刺激囊泡内Na⁺的积累，反之亦然。孵育1分钟后，刺激作用为无洛哌丁胺对照组的35%±5%（p<0.005）。洛哌丁胺还使回肠BBMVs中的Cl⁻/OH⁻逆向转运增加30%±5%（p<0.005）。此外，我们研究了Ca²⁺/钙调蛋白在洛哌丁胺对人BBMVs氯转运作用中的作用。在经洛哌丁胺预处理的BBMVs中，钙调蛋白活性显著降低（12±2对38±4皮摩尔/毫克蛋白质）。当经洛哌丁胺预处理的囊泡与2微摩尔/升钙（游离浓度）加5微摩尔/升钙调蛋白在5℃下孵育1小时时，观察到洛哌丁胺对Cl⁻/OH⁻逆向转运和Na⁺/Cl⁻协同转运的刺激作用完全被抑制。用2微摩尔/升钙加5微摩尔/升钙调蛋白增加经洛哌丁胺预处理的BBMVs的Ca²⁺/钙调蛋白活性，导致Cl⁻/OH⁻逆向转运和Na⁺/Cl⁻协同转运显著抑制40%±5%（p<0.005）。
