A Radioimmunoassay for Pancreatic-Glucagon in Chickens

Abstract

A radioimmunoassay was evaluated for determining pancreatic glucagon in plasma of chickens. The sensitivity of the radioimmunoassay was 7.5 pg/ml at 95% binding. Recovery of added porcine glucagon to chicken plasma samples had a correlation coefficient of 99.2%. Parallelism was demonstrated for the porcine glucagon standard and increasing aliquots of pooled chicken plasma which confirms the chicken pancreatic glucagon is immunologically similar to porcine glucagon. Parallelism was also demonstrated between porcine glucagon and acid-ethanol extracts of chicken pancreas (chicken pancreatic-glucagon). Since the cross-reactivity between acid-ethanol extracts of chicken pancreas and chicken intestine was only .03%, the antiserum is assumed t o be highly specific for measuring chicken pancreatic glucagon. The pancreatic glucagon in plasma of 2-week-old broiler chicks given continuous light ranged from 325 pg/ml at 1930 hr to 850 pg/ml at 0130 hr. Chicks given a 14:10 hr light-dark period contained a low plasma glucagon concentration of 390 pg/ml at 1630 hr and a high plasma glucagon concentration of 950 pg/ml at 0430 hr. Chicks fed 50% and 75% protein diets contained significantly (P<.05) increased levels (235 and 360 pg/ml, respectively) of plasma glucagon compared to chicks fed 25% protein diets. Chicks fasted for 48 hr had an increase in plasma glucagon compared to chicks fed starter diets; however, the increase was not significant (P>.05).