Angiotensin-converting enzyme inhibition and compliance of the carotid artery in normotensive and hypertensive rats.

To investigate the effects of local application of an angiotensin-converting enzyme inhibitor on the mechanical properties of the arterial wall, the volume/pressure relationship (from 25 to 175 mmHg) in the in vivo isolated carotid artery was measured in normotensive (WKY) and spontaneously hypertensive rats (SHR). The compliance of the carotid artery (CC) was calculated, for each level of pressure, as the slope of the the volume/pressure curve. The carotid artery was less compliant in the SHR strain than in normotensive rats. This rigidity was partly related to an increased tone of the arterial smooth muscle in SHR compared with the WKY. Local incubation with lisinopril (2.3 micrograms/ml) produced a significant increase in the compliance of the carotid artery in both normotensive and hypertensive rats; CC was increased by 23% in WKY rats and by 14% in SHR. Since the goal of antihypertensive treatment may be not only to reduce blood pressure (BP) but also to improve the mechanical properties of the arterial system, the direct effect of lisinopril on the arterial wall may have a major beneficial role.