twenty minutes before induction of anaesthesia , previously normotensive patients ( n = 35 ) , and patients with hypertension well controlled by beta-receptor antagonists ( n = 16 ) were pretreated with metoprolol ( m ) 0.2 mg kg-1 i.v . and dihydralazine ( dh ) 0.2 mg kg-1 i.v. , dihydralazine 0.2 mg kg-1 i.v . alone , or saline .
C0020538
hypertension
C0025859
metoprolol