INFLUENCES OF HEPARIN ON ACTH DISTRIBUTION AND IMMUNOREACTIVITY IN PLASMA OF THE RAT - INVIVO AND INVITRO STUDIES

  • 1 January 1980
    • journal article
    • research article
    • Vol. 76  (6) , 631-635
Abstract
Blood samples from non-pregnant female rats were incubated in vitro with porcine 125I-ACTH, and the corresponding plasmas were chromatographed on fine Sephadex G 50. When heparin was added in vivo or in vitro, almost all the radioactivity appeared in the void volume of the columns; the same was observed when labeled ACTH was added to heparin-containing saline. In contrast, when NaCl instead of heparin was added to the blood in vivo as well as in vitro, almost all the plasma radioactivity was eluted later, with 125I-ACTH. When labeled ACTH was i.v. administered to pregnant females, it was eluted in the void volume in the presence of heparin, and further down in its absence. The same plasma samples from non-stressed or ether-stressed females were radioimmunoassayed for ACTH, with and without heparin. The degradation of ACTH was greater in the presence of heparin, and plasma ACTH concentration was underestimated for low blood levels of heparin (5 IU/ml or less) and in contrast overestimated for high ones (25 or 50 IU/ml). Apparently heparin added to rat blood traps ACTH molecules, promoting the formation of aggregates with apparent high MW and heparin interferes with the direct radioimmunoassay of ACTH in the plasma.

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