Water-retention effect of suberogorgin was due to secretion of antidiuretic hormone in rat.

Aim: To study the mechanism of antidiuretic effect of suberogorgin (Sub).

Methods: Conscious rat was given i.g. Sub 3.16 mg.kg-1 20 min after water-loaded treatment and then urine was collected in metabolic cage. Ion excretion was determined in atomic emission spectrometry. Urinary prostaglandin E (PGE), plasma PGE, antidiuretic hormone (ADH), and aldosterone were measured with RIA. Sub vs pituitrin or DOCA effects were carried out in hypophysectomized or adrenalectomized rats.

Results: The urine volume and the excretions of urinary sodium and potassium were decreased, maximally by 91%, 76%, and 86%, during the 24-h period after Sub. This antidiuretic effect possessed a progressive weakening with time. The concentrations of urinary PGE, plasma PGE, and ADH were increased by 25%, 212%, and 538%, respectively, but plasma aldosterone was not significantly influenced, 2 h after Sub dosing. The response of urine-excretion of rat to Sub was almost resisted by hypophysectomy but not by adrenalectomy.

Conclusion: Sub decreased the urine excretion by, at least in part, accelerating the secretion of ADH but neither by PGE nor by aldosterone.