Rat pancreas contains the proglucagon(64-69) fragment and arginine stimulates its release

Rat proglucagon(64-69) corresponding to the C-terminal hexapeptide of putative rat glicentin sequence in the precursor was synthesized. A glicentin C-terminal hexapeptide specific radioimmunoassay, using the synthetic hexapeptide as standard, demonstrated the presence in rat pancreas of a peptide identified with the synthetic rat proglucagon(64-69): H-Asn-Arg-Asn-Asn-Ile-Ala-OH. The hexapeptide was released concomitantly with glucagon by arginine stimulation from the isolated perfused rat pancreas. The results indicate that the pancreas co-stores and possibly co-releases the hexapeptide with glucagon as one of the processing products of proglucagon.