Vaso-dilating drugs and the large arteries in essential hypertension.

Vasodilating drugs are commonly used in the treatment of hypertension. These antihypertensive agents are considered as acting on small arteries which are preferentially damaged in the hypertensive vascular disease. Recent studies have emphasized that the hemodynamic abnormalities in hypertension were not restricted to arterioles but involved also large arteries, resulting in a decrease in arterial compliance. This finding is potentially important since cardio-vascular morbidity and mortality in patients treated for hypertension is related to ischemic accidents related to alterations of large vessels, as observed in the coronary and the carotid-cerebral circulation. From this observation, it ensues that the study of the effects of vasodilating drugs on the large arteries of hypertensive patients should be extremely relevant to improve cardiovascular morbidity and mortality. On the basis of experimental studies, several cases of pharmacological dissociation in the dilatation of small and large arteries have been observed in animals, mainly in the coronary circulation. However, little research has been done on the effect of antihypertensive drugs on large arteries in men with essential hypertension. In the present review, the hemodynamic concepts and the methodologic basis for the study of large arteries in man are presented. Thereafter, the different aspect of the dilatation of small and large arteries in hypertension are analyzed, with the study of consequences on the conduit and the buffering functions of large arteries and on the development of cardiac hypertrophy. Finally, large arteries have also an important baroreflex function involved in the neuro-humoral consequences of vasodilatation. This point will be particularly described and interpreted.