Demonstration of a beta-casomorphin immunoreactive material in the plasma of newborn calves after milk intake.
Blood was collected from newborn calves before and after their first milk intake after birth; extracts of plasma were assayed by radioimmunoassay for the presence of beta-casomorphin-7 immunoreactive materials. No beta-casomorphin immunoreactivity was found in samples collected before milk ingestion; however, in samples collected after milk ingestion a beta-casomorphin-7 immunoreactive material was detected. Chromatographic characterization showed that this material was not identical with beta-casomorphin-7 but might rather represent a precursor thereof. The material proved resistant to enzymatic attack during a 30-min incubation period at 37 degrees C in the plasma of newborn calves, whereas beta-casomorphin-7 was degraded under these conditions. A physiological significance of beta-casomorphin-7 eventually cleaved from such a precursor material at any site in the newborn mammal is suggested.
D000818:Animals; D000831:Animals, Newborn / Q000097:blood*; D002364:Caseins / Q000378:metabolism; D002417:Cattle; D004723:Endorphins / Q000097:blood*; D008892:Milk / Q000378:metabolism*
D002364:Caseins; D004723:Endorphins; C021968:beta-casomorphins