Abstract
Summary
Fluorescent levels at 535 μ were measured in samples obtained from intact females, intact or hypophysectomized males, and ovariectomized females. Each sample was divided so that one part received no extraction with petroleum ether and the other portions received at least one extraction. The addition of this step failed to alter significantly the fluorescent levels in samples from male rats or ovariectomized females. In the latter group, occasional pairs of samples showed differences of at least 5 μg% plasma. In contrast, fluorescent values declined following a single extraction with petroleum ether in samples obtained from intact females at all stages of the estrous cycle. A second extraction produced only small changes (<2.5 μg% plasma).
These data support the hypothesis that the main interfering fluorogen in the fluorimetric determination of plasma levels of corticosterone is secreted by the ovary. A likely candidate is 20α-hydroxypregn-4-en-3-one. The extraction of the plasma with petroleum ether may be safely omitted in samples obtained from male rats. This reduces the time required to determine corticosterone levels.
The author is grateful to Drs. M. A. Slusher and G. Newton for helpful suggestions during this study.
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