Studies on passive immunity in the foal: II. The absorption of 125I-labelled PVP (polyvinyl pyrrolidone) by the neonatal intestine

Abstract

An iodinated marker, 125I-PVP K·60, (polyvinyl pyrrolidone) of mean molecular weight, 160 000, was shown to be well absorbed from the intestine of the newly born foal. The absorption was maximal (22 per cent.) 3 h. after birth, but fell rapidly in a linear decline to less than 1 per cent. by 20 h. of life. There was reduced absorption (10 per cent.) when the foals were deprived of colostrum although the time of cessation of uptake did not alter. The figures for the percentage absorption represented only the apparent efficiency of absorption as only intravascular PVP was measured. The real efficiency would be expected to be approximately doubled taking into account the extravascular pool of PVP. PVP introduced into the stomach of newly born foals reached peak levels of radioactivity 6 h. after administration. There was apparently no degradation of the PVP molecule during the process of uptake and transfer to the systemic circulation. However high levels of PVP were excreted in the urine up to 9 h. after birth. After this time the levels declined until by 28 h. very little radioactivity was detectable in the urine. The molecular size of the urinary PVP was 11 000 to 20 000.