Pharmacokinetics and organ distribution of the sorbin C-terminal peptides

Sorbin is a 153 amino acid peptide isolated from porcine small intestine. The heptapeptide-amide is the minimal active site of the natural molecule. A comparison of the distribution of C-7 and C-20 sorbin, which have been shown to share the activity of sorbin in increasing intestinal absorption of electrolytes, was undertaken by radioimmunoassay, after perfusion of 200 micrograms/kg/h. A longer half-life in plasma was observed for C-20 sorbin than for C-7 sorbin, with a clearance rate of 18 +/- 4 ml/min/kg vs. 40.6 +/- 13.5 ml/min/kg and a distribution volume of 192 +/- 35 ml/kg vs. 286 +/- 123 ml/kg. The accumulation of tritiated C-7 sorbin was observed in enterocytes, serosal acini of the salivary glands, and fundus chief cells. The recovery of intact peptide in the intestine was 0.06% per gram of tissue. Eighteen percent of the peptide was detected in urine.