Lima A A, Monteiro H S, Fonteles M C
Clinical Research Unit, School of Medicine, Federal University of Ceará, Fortaleza, Brazil.
Pharmacol Toxicol. 1992 Mar;70(3):163-7. doi: 10.1111/j.1600-0773.1992.tb00449.x.
To compare the function of sodium transport between intestine and renal tubule, we studied the effect of E. coli STa enterotoxin and 8-bromo cyclic GMP in perfused rat kidneys. Infusion of STa enterotoxin (0.017 and 0.1 micrograms/ml) caused a dose and time dependent decrease in total renal sodium tubular transport. The major site of STa effect was at the renal proximal tubule. Similar to Sta enterotoxin, 8-bromo cyclic GMP (10(-5) M) caused a significant decrease of fractional renal sodium proximal tubule transport. In contrast to STa enterotoxin, infusion of 8-bromo cyclic GMP resulted in a significant but short lasting (30 min.) increase in glomerular filtration rate. STa enterotoxin also decreased significantly the renal tissue potassium. This STa effect was related to a significant decrease in renal potassium tubular transport, resulting also in an increase of urinary potassium excretion. These studies demonstrate the specific functional effect of STa enterotoxin in promoting the decrease in renal proximal tubular sodium transport, similar to 8-bromo cyclic GMP. In perfused rat kidneys STa also decreased tissue potassium, mainly by a decrease in potassium transport and increase in urinary potassium excretion. These effects suggest the existence of an endogenous peptide resembling STa enterotoxin, that regulates the function of renal sodium tubular transport.
为比较肠道和肾小管中钠转运的功能，我们研究了大肠杆菌STa肠毒素和8-溴环鸟苷酸对灌注大鼠肾脏的影响。输注STa肠毒素（0.017和0.1微克/毫升）导致肾钠总肾小管转运呈剂量和时间依赖性下降。STa作用的主要部位是肾近端小管。与STa肠毒素相似，8-溴环鸟苷酸（10^(-5) M）导致肾近端小管钠分数转运显著下降。与STa肠毒素不同的是，输注8-溴环鸟苷酸导致肾小球滤过率显著但短暂（30分钟）升高。STa肠毒素还显著降低了肾组织钾含量。这种STa作用与肾钾肾小管转运显著下降有关，也导致尿钾排泄增加。这些研究证明了STa肠毒素在促进肾近端小管钠转运下降方面的特定功能作用，类似于8-溴环鸟苷酸。在灌注大鼠肾脏中，STa还降低了组织钾含量，主要是通过减少钾转运和增加尿钾排泄。这些作用表明存在一种类似于STa肠毒素的内源性肽，它调节肾钠肾小管转运的功能。
