The Effect of Labetalol on the Pressure Responses to Isometric Exercise and a Cold Pressor Test in Pregnancy-Induced Hypertension

Ten patients with pregnancy-induced hypertension were subjected to an isometric handgrip exercise test (IHG) and a cold pressor test (CPT) before and during treatment with oral labetalol 200mg three times daily. The drug reduced resting blood pressure but not heart rate. During IHG heart rate and mean arterial blood pressure increased significantly both before and during treatment. Treatment did, however, not attenuate the responses. During CPT blood pressure increased significantly both before and during treatment without significant difference between the two occasions. Heart rate remained essentially unchanged both before and during labetalol treatment. It is suggested that not only the traditional measuring of resting blood pressure but also the blood pressure response to physical stress should be taken into account as indicator of the effect of an antihypertensive treatment in pregnancy-induced hypertension.