Molecular forms of peptide histidine isoleucine-like immunoreactivity in the gastrointestinal tract. Nonequimolar levels of peptide histidine isoleucine and vasoactive intestinal peptide in the stomach explained by the presence of a big peptide histidine isoleucine-like molecule.
Regional specific antibodies and chromatography were used to analyze the distributions and molecular forms of peptide histidine isoleucine (PHI) and vasoactive intestinal peptide (VIP) in the porcine intestine. Both peptides were present along the entire length of the intestine, the highest concentrations occurring in the colon. Concentrations of PHI immunoreactivity, measured with three different antisera, and VIP immunoreactivity were approximately equal in all parts of the gastrointestinal tract except in the stomach. In the stomach, the concentration of PHI immunoreactivity, measured with the N-terminally directed antibody R8403, although equal to the corresponding VIP concentration, was two to four times higher than the PHI immunoreactivity detected with the two C-terminally directed PHI antisera T33 and T41. Chromatographic analysis on Sephadex G-50 superfine of gastric extracts revealed only one VIP immunoreactive peak that eluted in the same position as the porcine VIP standard, at Kav 0.53. A PHI immunoreactive peak was also detected with the C-terminally directed PHI antisera in the same position as porcine PHI standard. However, with the N-terminally directed PHI antiserum R8403, an additional PHI immunoreactive peak was detected in gastric extracts constituting the predominant form present, and this peak eluted earlier at Kav 0.37. The PHI immunoreactive material that eluted earlier was present in the rest of the intestine in only small amounts. As VIP and PHI are believed to be derived from a common precursor, it is suggested that in the stomach the posttranslational enzymic processing of the precursor is different from that in the other parts of the intestine.
D000818:Animals; D000906:Antibodies / Q000032:analysis; D000918:Antibody Specificity; D002415:Cats; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D003429:Cross Reactions; D004064:Digestive System / Q000276:immunology; D006801:Humans; D007120:Immunochemistry; D046911:Macromolecular Substances; D010451:Peptide PHI; D010455:Peptides / Q000032:analysis / Q000276:immunology*; D011863:Radioimmunoassay; D051381:Rats; D013270:Stomach / Q000276:immunology*; D013552:Swine; D014660:Vasoactive Intestinal Peptide / Q000032:analysis / Q000276:immunology*
D000906:Antibodies; D046911:Macromolecular Substances; D010451:Peptide PHI; D010455:Peptides; D014660:Vasoactive Intestinal Peptide