Actions of Calcium Channel Blockers on Vascular Proteoglycan Synthesis: Relationship to Atherosclerosis

Abstract

Calcium channel blockers (CCBs) are a widely used group of antihypertensive agents. CCBs are efficacious in the reduction of blood pressure but the extent to which they manifest beneficial effects on cardiovascular disease is variable. Clinical studies indicate that pleiotropic actions make significant contributions to the efficacy of agents aimed at preventing atherosclerosis. The “response to retention” hypothesis implicates the binding and retention of lipoproteins by glycosaminoglycan chains on proteoglycans as an initiating step in atherogenesis. Atherogenic factors act as agonists and several classes of drugs including peroxisome proliferating-activated receptor (PPAR)-α and -γ ligands act as antagonists in this model. Initial data have demonstrated that high concentrations of CCBs inhibit proteoglycan synthesis. Newer preliminary data show that the action is very modest at reasonable concentrations and appears to be independent of calcium channel blocking activity. We have reviewed the role of cardiovascular drugs acting on vascular smooth muscle proteoglycan synthesis and considered the potential action of CCBs in this model. We conclude that the inhibition of proteoglycan synthesis by CCBs does not play a role in the attenuation of atherosclerosis; however, the antihypertensive efficacy and alternative beneficial actions provide support for the use of CCBs in the therapy of cardiovascular disease.

Keywords:

• atherosclerosis
• calcium channel blockers
• cardiovascular disease
• lipoprotein
• proteoglycans

Acknowledgements

Research in the laboratory is supported by the National Health and Medical Research Council of Australia and the Alfred Hospital Foundation. The stereoisomers of amlodipine were kindly supplied by Pfizer Pty Ltd, West Ryde, Australia.