Impedance spectra in the abdominal aorta of dogs: response to vasoactive drugs

Impedance spectra were measured in the abdominal aorta of dogs under normal and altered physiological states. A bolus injection of norepinephrine was given to provide an acute simulation of a hypertensive state. Nitroprusside, a common antihypertensive agent, is infused to indicate the effects of vasodilation. Norepinephrine induces an increase in impedance modulus and a corresponding reduction in phase angle relative to a normal state. Nitroprusside´s effects are just opposite to those of norepinephrine