Conversion of Radiolabeled Human Growth Hormone into Higher Molecular Weight Moieties in Human Plasma in Vivo and in Vitro
1977; Oxford University Press; Volume: 101; Issue: 2 Linguagem: Inglês
10.1210/endo-101-2-350
ISSN1945-7170
AutoresInese Z. Beitins, Mario C. Rattazzi, Margaret H. MacGillivray,
Tópico(s)Metabolism, Diabetes, and Cancer
ResumoPurified human growth hormone (hGH) was iodinated with 131I ([131I]iodo-hGH) and purified on Sephadex G-100. The monomeric [131I]iodo-hGH (mol wt about 20,000 daltons) was injected as a bolus iv in healthy volunteers and plasma obtained at 10,20, and 40 min. Then continuous infusion with [13II]- iodo-hGH was started and further plasma samples obtained after 120 min when a plateau of immunoreactive hGH (IR-hGH) had been attained. In one individual the bolus injection was followed further to 60 and 120 min. Fresh plasma was immediately chromatographed on Sephadex G-100 and the IR-hGH profiles evaluated. In all instances following iv injection, larger and occasionally smaller immunoreactive moieties than the injected [131I]iodo-hGH appeared. When [131I]iodo-hGH was incubated at 37 C with fresh human plasma from 4 different individuals from 10 to 120 min, the larger molecular weight forms, noted in the in vivo studies, were again demonstrable. Only the monomeric [13lI]iodo-hGH was found when [131I]iodo-hGH was incubated at 37 C for 120 min with human serum albumin or gamma globulin.
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