naloxone [ 0.4 mg iv . ] increased blood pressure and heart rate of 13 clonidine-treated [ 0.3 mg per os for 3 days ] patients with essential hypertension [ reacting group ] while it has no such effect in 11 clonidine-treated patients [ non-reacting gr . ]
C0020538
increased blood pressure
C0009014
clonidine