Effect of verapamil on intimal thickening and vascular reactivity in the collared carotid artery of the rabbit

WOS: A1996VA41100017PubMed ID: 88424321 Intimal thickening is a common site for atherosclerosis. Therefore, we investigated whether the calcium entry blocker verapamil (10 mg kg(-1) body weight day(-1), s.c.) can retard intimal thickening and changes in vascular reactivity induced by a non-occlusive, silicone collar positioned around the left carotid artery of rabbits. The contralateral carotid artery was sham-operated and served as a control. 2 Verapamil and placebo (saline 0.1 ml kg(-1) day(-1), s.c.) treatments were initiated 7 days before placing the collar and lasted 3 weeks. Thereafter, segments were cut from collared and sham-treated arteries for histology and isometric tension recording. 3 The intima/media (I/M) ratio increased after 14 days of collar treatment, but intimal thickening was not inhibited by verapamil (I/M ratio placebo 0.31+/-0.07, verapamil 0.32+/-0.09). 4 The collar decreased the capacity to develop force, as indicated by the response to a supramaximal concentration of KCl, decreased the sensitivity (pD(2)) to acetylcholine (ACh) and phenylephrine (Phe), but increased the sensitivity to 5-hydroxytryptamine (5-HT). 5 Although verapamil did not affect intimal thickening, it normalized the hypersensitivity to 5-HT in collared arteries. 6 The contraction to the supramaximal concentration of KCl was not affected by verapamil. Verapamil decreased the E(max) of ACh, but this was only seen in collar-treated arteries. Verapamil also decreased the sensitivity to ACh and Phe, in both sham- and collar-treated arteries. 7 We conclude that verapamil, without preventing thickening of the intima, can modify collar-induced changes in vascular reactivity