Animals
with a systemic blood pressure higher than 180
mmHg were employed for the screening of antihypertensive activity. Tannins for testing were
dissolved in the Locke Ringer solution. After iv
injection of each substance at the desired concentration, systemic blood pressure was measured at
10-min intervals. Lowering of tail arterial blood
pressure at a level of 5% or more, compared to
control before administration of testing compound, was considered significant (pc0.05).
Only a substance that produced a hypotensive effect lasting 30 min or longer was considered to
possess antihypertensive activity