ADRENOCORTICOTROPIN-INDUCED HYPERTENSION IN RATS - ROLE OF OUABAIN-LIKE COMPOUND

We examined the role of ouabain-like compound (OLC) in hypertension as sociated with corticotropin (ACTH) excess in rats. Physiological salin e solution (1 mL/kg) or synthetic ACTH-Z (0.5 mg/kg) was injected intr amuscularly for 15 days to 14 control and 13 male Wistar rats. Signifi cant increases in blood pressure and plasma sodium/potassium ratio, an d decreases in plasma potassium concentration and urinary sodium/potas sium ratio were observed in ACTH-treated rats. The plasma OLC level wa s higher in ACTH-treated group (control; 76 +/- 13, ACTH; 202 +/- 48 p mol/L, P <.05). Plasma OLC level correlated with systolic blood pressu re (SPB; r = 0.53, P <.01). Urinary OLC excretion was also higher in A CTH-treated group (control; 0.95 +/- 0.01, ACTH; 3.32 +/- 0.67 pmol/da y, P <.01). A significant relation was also found between urinary OLC excretion and SEP (r = 0.66, P <.01). Plasma potassium concentration n egatively correlated with SEP (r = -0.48, P <.01) and urinary sodium/p otassium ratio also correlated inversely with urinary OLC excretion (r = -0.55, P <.01). Measurement of OLC levels after the fractionation o f urine by reverse-phase high performance liquid chromatography showed that the major OLC peak in urine from both groups coincided with that df authentic ouabain. These results suggest the contribution of OLC t o ACTH-induced hypertension in rats. (C) 1997 American Journal of Hype rtension, Ltd.