Human salivary or plasma aldosterone- and dehydroepiandrosterone-binding glycoprotein induces hypertension in the rat

In this study we demonstrated the presence of an aldosterone-binding globulin (ABG) in human saliva. Following ultrafiltration and purification of saliva to electrophoretic homogeneity, this thermolabile globulin called ABG-S appeared to be identical to plasma ABG. It was also shown that both purified ABG-S and plasma ABG bind reversibly, with high affinity (Ka = 1.6 X 10(-9) M, Scatchard plot) to dehydroepiandrosterone sulfate (DHEA-S) to binding sites different from those for aldosterone. Following incubation with human urine both ABG and ABG-S were converted quantitatively into corresponding thermostable forms which appeared to be identical with the human urinary ABG homologue namely ABG-TsU. In addition ABG-S showed the same ability to elevate blood pressure when administered to rats as did ABG-TsU. The fact that an endogenous substance with pressor activity might exist in more than one body fluid suggests further its possible participation in the basic mechanisms of blood pressure regulation.