PARALLEL MEASUREMENTS OF INDOLE AND SKATOLE (3-METHYLINDOLE) IN FECES AND BLOOD-PLASMA OF PIGS BY HPLC

Skatole and indole (partly) result from microbial degradation of tryptophan in the intestine and may cause an unpleasant fecal odour of pork. A high-performance liquid chromatography method was developed which allows serial measurements (sensitivity, 0.15 ng/ml plasma; coefficient of variation, 10%). Parallel measurements were carried out in blood plasma, drawn through indwelling catheters in the jugular vein and the vena cava, from five ovariectomized sows. Additional determinations were carried out in feces. Concentrations in feces (skatole, xBAR=2.3 mug/g; indole, xBAR=10 mug/g) were significantly correlated (P less-than-or-equal-to 0.001) with concentrations in jugular vein plasma. Skatole concentrations in plasma of vena cava (xBAR=0.54 ng/ml) were higher (P less-than-or-equal-to 0.001) than in peripheral plasma (0.32 ng/ml). In plasma of the portal vein, concentrations of skatole were 67 ng/ml and those of indole 120 ng/ml. It is concluded that changes in fecal concentration indicate similar changes in blood concentrations. Indole formation is higher than skatole formation and occurs mainly in the proximal part of the large intestine, so that the vena cava does not contribute to peripheral concentrations. Skatole formation also occurs in the distal part, and the vena cava plasma reflects considerable resorption, whereas indole concentrations do not differ significantly in both vessels.