Studies on uremic toxins: the identification and the determination of toxic effect by tissue culture method.

Uremic serum fractions obtained by Amicon XM-10 hollow fiber and membrane filtration was investigated using cytotoxicity in tissue culture by Rose's circumfusion system and by monolayer culture. The cytotoxic fraction was investigated with Elphor-Va 4, IR spectrometry, mass spectrometry, and NMR spectrometry for analysis of the true form of the substance. Remarkable cytotoxicity was observed in the small molecular fraction. Of the substances which may be surmised as uremic toxins, such as urea methylguanidine (MG), guanidinosuccinic acid, etc., only MG presented a similar cytotoxicity to this fraction. From the result of mass spectrometry, infrared spectrometry, and NMR spectrometry, it appeard that the electropositive substance included in the small molecular fraction was intimately associated with MG or one of its derivatives. The middle molecular fraction showed an inhibitory effect on cultured mouse liver glucokinase and human erythrocytic Na-K-dependent ATPase.