Effects of age and hypertension on cardiac responses to the α1-agonist phenylephrine in humans

57 human subjects, comprising 14 young healthy volunteers (mean age 30+/-1 years), 18 older healthy volunteers (mean age 60+/-1 years), 10 young hypertensive subjects (mean age 36+/-1 years), and 15 older hypertensive subjects (mean age 58+/-1 years).

Phenylephrine administered at four incremental rates for 8 min each.

Comparisons across four groups: young normotensive, older normotensive, young hypertensive, and older hypertensive subjects.

Blood pressure, heart rate, and left ventricular responses assessed by echocardiography.surrogate