Quantitation of Epidermal Growth Factor in the Rat

Abstract

Epidermal growth factor (EGF) was purified from the rat submandibular gland to establish a radioimmunoassay. Detectable amounts of EGF were found in the rat duodenum (median, 0.55 pmol/duodenum; range, 0.38-0.68 pmol/duodenum; n = 10) and duodenal juice (median, 215 pmol/l; range, 95-468 pmol/l; n = 10), whereas no EGF was detected in the jejunal extracts. Submandibular and duodenal EGF each consisted of 2 isopeptides (pI [isoelectric point] 4.8, 5.4, and 5.5, 6.0, respectively). The peptides behaved alike both with regard to immunoreactivity (radioimmunoassay) and receptor binding (radioreceptor assay). The present data combined with previous results suggest a role for EGF in the gastrointestinal tract.