Erucamide as a modulator of water balance: new function of a fatty acid amide.

The aim of this study was to isolate a compound from blood plasma that inhibits intestinal diarrhea and that appears also to regulate fluid volumes in other organs. The isolation procedure included lipid extraction, liquid chromatography, and gas chromatography. The active substance was identified by mass spectrometry as erucamide (MW 337 Da). The biological effect was reproduced with authentic erucamide. Erucamide is a fatty acid amide, such as oleamide and anandamide, which modulate other physiological functions in a receptor-mediated fashion. All the exact biological functions of erucamide are as yet to be defined, but it is already known to stimulate angiogenesis. Erucamide concentrations were determined in body organs from the pig. The blood plasma level was 3 ng/g, and those of lung, kidney, liver, and brain were 12, 2.5, 1.0, and 0.5 ng/g, respectively. Erucamide was below detection level in the intestine, but is known to be present in the cerebrospinal fluid. In the rat, 3H-erucamide was accumulated in vivo into lung, liver, and spleen and in vitro into lung, liver, brain, and intestine. The in vitro uptake was time and temperature dependent, but not saturable.