Absorption, secretion and excretion of dimethylamine in rats.

The dimethylamine (DMA) concentration in the gastrointestinal tract of Wistar male rats fed a commercial diet containing 23.6 mg/kg DMA was highest (11.2 +/- 2.1 mg/kg) in the stomach and decreased from the upper region to the lower region. In contrast, the highest DMA concentration (6.6 +/- 2.5 mg/kg) in the upper small intestine was observed in rats fed a low-DMA diet containing 1.0 mg/kg DMA. DMA absorption was observed in the intestines and the absorbtion curves were monoexponential. The biological half-lives (t1/2) of DMA in the ligated stomach, upper and lower small intestine, caecum and large intestine were 198, 8.3, 11.6, 31.5 and 11.0 min, respectively. The DMA concentration in blood increased from 0.3 +/- 0.1 mg/kg to 3.0 +/- 1.0 mg/kg 5 min after injection of 250 micrograms DMA into the ligated upper small intestine. The disappearance curve of DMA in blood was monoexponential and the half-life for the initial 15 min was 12.5 min when 250 micrograms DMA were injected through a femoral vein. Intestinal secretion of DMA (15.6 +/- 12.6 mg/kg) was observed 15 min after the injection. Urinary DMA increased from 17.3 +/- 9.4 to 139 +/- 23 mg/kg within 30 min of intravenous injection of DMA. These results show that the behaviour of DMA in rats is as follows: (Formula: see text)