Serum protein fluxes between the vasculature and tissues of the hindlimbs in calves fed soy or urea purified diets

Abstract

Proteins in the arterial and venous sera collected from the hindlimbs of calves. fed purified diets under steady state conditions with soy protein or urea providing all dietary nitrogen were examined. Ion-exchange chromatography provided an initial fractionation into four groups of proteins. The proteins within each group were subsequently evaluated by disc-gel electrophoresis. Proteins having the same Rf were compared between diets with regard to the relative involvement of individual proteins in both diets. No dietary difference in the venous levels of a protein were observed. Urea-fed calves, however, displayed a substantial flux of proteins between the vasculature and tissues of the hindlimbs. One group of proteins (F-I), apparently beta-globulins, were found to be in a much higher venous than arterial concentration indicating a substantial release of these proteins from the tissues of the hindlimbs. The same response was not observed in soy-fed calves. A second group of proteins (F-II) in the urea-fed calves moved in an opposite manner to F-I. No consistent redistribution of protein was apparent in the calves fed soy protein. A change in the normal distribution and movement of serum proteins in the hindlimbs of calves is implicated when high levels of urea are fed.