it was found that , after pretreatment with phenoxybenzamine ( 1.5 mg/kg , i.v . ) an infusion of st 91 ( 8 microgram/kg/min , 2 min ) produced a much diminished pressor response and a later small hypotension , while still causing the same degree of bradycardia .
C0031441
phenoxybenzamine
C0020649
hypotension