We determined alterations in renal aquaporin-2 (AQP2) gene expression in association with impaired water excretion in glucocorticoid-deficient rats. After adrenalectomy, Sprague-Dawley rats were administered aldosterone alone by osmotic pumps (glucocorticoid-deficient rats). As a control, both aldosterone and dexamethasone were administered. These animals were subjected to the studies on days 7–14. The expressions of AQP2 mRNA and protein in kidney of the glucocorticoid-deficient rats were increased by 1.6- and 1.4-fold compared with the control rats, respectively. An acute oral water load test verified the marked impairment in water excretion in the glucocorticoid-deficient rats. One hour after the water load, the expressions of AQP2 mRNA and protein were significantly reduced in the control rats, but they remained unchanged in the glucocorticoid-deficient rats. However, there was no alteration in [3H]arginine vasopressin (AVP) receptor binding and AVP V2 receptor mRNA expression in the glucocorticoid-deficient rats. A V2-receptor antagonist abolished the increased expressions of AQP2 mRNA and protein in the glucocorticoid-deficient rats. These results indicate that augmented expression of AQP2 participates in impaired water excretion, dependent on AVP, in glucocorticoid deficiency.
Perfusion Nutrient Load Test Combined With 2dus in Assessment of Proximal and Distal Gastric Emptying in Healthy Subjects and Functional Dyspepsia Patients
