CARDIOVASCULAR-RESPONSE TO PHYSICAL STRESS IN OFFSPRING OF HYPERTENSIVE PARENTS - DUTCH HYPERTENSION AND OFFSPRING STUDY

Blood pressure (BP) regulatory mechanisms were studied in youngsters w ith contrasting risks for hypertension, based on parental history, dur ing physical stress. As a static exercise, an isometric handgrip task (22% of maximal force during 5 min) was used and a dynamic exercise ta sk was performed on a bicycle ergometer, At rest and during stress, BP and heart rate were recorded. In order to study the adaptation of the cardiovascular system to physical stress, cardiac output and total pe ripheral resistance were measured in addition to indices of vagal and sympathetic influences on the heart. Heart rate and cardiac output dec lined significantly more in offspring of hypertensive parents during s tatic exercise (difference in heart rate: -2.5 +/- 1.2 bpm, P=0.04; di fference in cardic output: -9.0 +/- 4.6%, P=0.05). This is most likely the result of a larger blunted in offspring of hypertensive parents. increase in the total peripheral resistance in youngsters at risk (dif ference: 13.2 +/- 6.8%, P=0.06). No differences between the two groups were found in reactivity of BP or in the indices of sympathetic activ ation or vagal inhibition of the heart. The offspring of hypertensive parents showed an attenuated increase in stroke volume during the dyna mic exercise task (difference at the first cycling level: -11.5 +/- 5. 4%, P=0.04), while no difference in neural activity or heart rate was found, Youngsters with a parental history of hypertension show an enha nced reactivity of total peripheral resistance during static exercise. This does not lead to a higher BP response in this group, most probab ly because of a larger decrease of the cardiac output. During dynamic exercise the physiological increase in stroke volume is blunted in off spring of hypertensive parents.