A radioimmunoassay for the measurement of rat pancreatic polypeptide (RPP) in serum or plasma has been developed and characterized using a new guinea-pig anti-rat-PP antibody. The assay provides a high degree of sensitivity and lacks cross-reactivity (CR < 0.01%) to neuropeptide Y and peptide YY. It also does not interact with PPs of other species or peptide hormones namely, amylin, glucagon, human insulin, human-PP, human-proinsulin, rat C-peptide and rat insulin. The assay employs synthetic rat PP as standards from concentrations of 21-2100 pg/ml (i.e., 5-500 pM) and produces a sensitivity limit of 19 pg/ml (4.5 pM) PP at ?? 3 S.D. The intra- and interassay % coefficient of variations are 6.4% and 5.9%, respectively. The % recovery of RPP added to rat serum samples ranges from 98% to 103%. Assay of serum volumes ranging from 25 ??l to 100 ??l does not significantly alter the expected RPP level. The migration patterns of rat serum PP and that of a synthetic RPP are identical by Sephadex G-50 chromatographic analysis. The mean values of fasting and a 2 h post-feeding plasma RPP levels in normal rats are 40 ?? 2 and 80 ?? 10 pg/ml (9.5 pM and 19.0 pM), respectively. Rat-PP release during insulin induced hypoglycemia in conscious rats rises from 38 ?? 5 pg/ml to 261 ?? 34 pg/ml (9.0 to 62.1 pM, P < 0.005) by 30 min. Additionally, the antibody used in this study cross-reacts well with mouse-PP as determined by linear serum dilution curves, thus making it useful in the measurement of murine-PP. In conclusion, we have developed and validated a sensitive and specific rat-PP assay. This assay provides a new tool for the reliable measurement of PP in physiologic studies using rat and mouse animal models. ?? 1992.
Akpan, J. O., Havel, P. J., Parry, S. J., Shalwitz, R. A., & Gingerich, R. L. (1992). The characterization of radioimmunoassay for rat pancreatic polypeptide in serum. Regulatory Peptides, 37(1), 59–69. https://doi.org/10.1016/0167-0115(92)90064-2