Radioimmunoassay and intramural distribution of PHI-IR in human intestine.

The objective of this study was to develop a radioimmunoassay for PHI and use this to assess its intramural distribution in the human intestine. The antibody was harvested following immunization with porcine PHI conjugated to bovine serum albumin by glutaraldehyde, and the iodinated PHI tracer was prepared by the Iodo-gen method. The assay system showed no cross-reaction with other members of the glucagon-secretin family of peptides and was sensitive to changes of PHI of 2 fmol/tube (95% confidence). High concentrations of immunoreactive PHI were found in the human intestine, exclusively localized in the nonendocrine gut layers, suggesting a possible neuroendocrinological or neurotransmitter role for PHI

Distribution and molecular heterogeneity of galanin in human, pig, guinea pig, and rat gastrointestinal tracts.

Galanin was measured by radioimmunoassay in whole thickness extracts of the gastrointestinal wall from four species and in extracts from separate layers of human small intestine. The immunoreactivity was characterized using gelchromatography and high-pressure liquid chromatography. Two antibodies were employed, which were characterized as non-C-terminal (Gal 8) and C-terminal (Gal 9) using a C-terminal galanin 10-29 fragment. Substantial quantities of galanin immunoreactivity were found, mainly localized at the muscle layer. Both intramolecular and intermolecular heterogeneity was apparent. Two molecular forms exist in humans (Kav 0.58, 0.69). The molecular heterogeneity in humans, rats, and guinea pigs may be localized near the C-terminus of the galanin molecule. A C-terminal extension of one human galanin form is likely (Kav 0.58). These findings give radioimmunologic evidence for a neurocrine origin of galanin. The chromatographic variations suggest that extrapolation of experimental result