Vasoactive drugs and elastic properties of human arteries in vivo, with special reference to the action of nitroglycerine.

Pulsatile changes in the volume of an arm segment were recorded with an air-filled plethysmograph and related to intra-arterial blood pressure. Alterations in transmural arterial pressure were obtained by changing the pressure in a large chamber surrounding the entire arm. Arterial compliance values were calculated in late diastole when pressure and volume changes were slow. Compliance varied with transmural arterial pressure in a hyperbolic manner, rising steeply at low pressure. Noradrenaline and hypertensin did not change the arterial compliance values, while dihydroergotamine reduced them. Nitroglycerine caused a pronounced increase in compliance values in doses that did not change cardiac output and arterial pressure.