Abstract
Abstract. Corticosteroid binding globulin (CBG) was detected by a specific radioimmunoassay in mixed saliva (25.4 ± 4.0 μg/l, mean ± sem) and in pure, uncontaminated parotid fluids (17.4 ± 2.7 μg/l) at resting flowrates of approximately 500 μl/min and 50 μl/gland per min, respectively. In parotid fluids collected at stimulated flow-rates of between 300–1000 μl/gland per min, CBG could not be detected. This observation suggests the direct flow-rate-dependent transfer/secretion of CBG in saliva. When cortisol was measured (RIA) in dilution experiments in both mixed saliva and parotid fluids using phosphate buffer at pH 7.4 as diluent, a protein-binding effect analogous to that found in plasma samples was observed. However, this effect was abolished if a known CBG inhibitor, phosphate:citrate buffer at pH 4, was used as the diluent in the assay. A bound fraction of cortisol was found in both mixed saliva (14.0 ± 4.0%) and parotid fluid samples (12.3 ± 1.3%) by equilibrium dialysis. These findings appear to contradict the currently accepted notion that specific plasma steroid binding proteins, and hence the protein-bound steroids, are absent in uncontaminated saliva; and that their presence in mixed saliva is the consequence solely of contamination by gingival fluid and/or plasma from mouth or gum abrasions. We conclude that both protein-bound and free steroids are present in uncontaminated saliva and that salivary total and plasma free steroid concentrations are not identical.
Subject
Endocrinology,General Medicine,Endocrinology, Diabetes and Metabolism
Cited by
23 articles.
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