EFFECTOFLABETALOLINHYPERTENSION DURINGEXERCISE AND POSTURALCHANGES

1 Fourteen hypertensive patients were studied byintra-arterial BP monitoring toquantify the effects ofstandardized physiological stresses: Valsalva manoeuvre, isometric, treadmill andbicycle exercise, and600tilting before andafter labetalol treatment. 2 Thedoseoflabetalol ranged from100-600 mg three times daily andtheresponsewas judged on outpatient clinic recordings. 3 Thedrugproduced asustained reduction ofBPandheart rateresponsesduring dynamic exercise andtheValsalva manoeuvre,butthedegree ofchange fromthelowered baseline were notchanged by labetalol. Thefall inBPon cessation ofexercise was decreased rather thanincreased. 4 Theresponsetocontrolled isometric muscle contraction was affected ina similar fashion. 5 Tilting produced a fall inBPafter treatment, andthis was mostmarkedinthose patients on the highest doses. However, compensatory increases indiastolic BPwereobserved.