Effects of labetalol in chronic two-kidney Goldblatt hypertension (2-KGH) in rats.

Labetalol administered intra-gastrically in a dose of 30 mg/kg twice a day for 3 weeks significantly lowered systolic tail blood pressure (STBP) in chronic two-kidney Goldblatt hypertension in rats. Hypotensive response of labetalol in normotensive rats has also been demonstrated. Plasma renin activity (PRA) measured at the end of the treatment was similar in labetalol-treated and in dextrose-treated rats. The bradycardial response was evident in both hypertensive as well as in normotensive animals; however,, this change was statistically significant for the hypertensive rats only. Hypertension was associated with increase in the heart weight, which was not affected by labetalol treatment. Antihypertensive effect of labetalol is neither related to renin suppression nor to beta blockade.