Study on the mechanisms of glucocorticoid-induced hypertension: glucocorticoids increase transmembrane Ca2+ influx in vascular smooth muscle in vivo.

Blood pressure (BP) and ex vivo influx rate of Ca2+ in excised aortae were measured in rabbits implanted with silastic rubber strips impregnated with glucocorticoids (GC) [dexamethasone (DEX) or cortisol (FK)], or carbenoxolone (CX) [inhibitor of 11 beta-hydroxysteroid dehydrogenase (11-HSD), in a large (lg) or a small (sm) (10 times smaller) concentration], or FK plus CX (sm), or DEX plus RU 38486 (a specific GC-receptor blocker). After 4-6 weeks rabbits implanted with DEX, CX (lg), and FK+CK (sm) developed hypertension. Those implanted with FK alone (yielding physiological serum concentration of FK), CX (sm), and DEX+RU 38486 did not develop hypertension.