Affiliations: [a] Department of Cardiology, Catheterization Laboratory, Evangelismos General Hospital, Athens, Greece | [b] Laboratory of Biomechanics, Center of Clinical, Experimental Surgery, and Translational Research, Biomedical Research Foundation of the Academy of Athens, Athens, Greece
Abstract: Background:Limited attention has been paid to the role of beta-adrenergic blocking agents on large artery function/structure, despite being clinically useful for treating many forms of cardiovascular disease. Objective:To assess long-term consequences of beta-blocker administration on the biomechanical properties, geometry, and histological structure of two major elastic arteries. Methods:Healthy male rats received water with their food, while beta-blockade was produced in rats by adding propranolol in their drinking water. The thoracic aorta and carotid artery were resected after three months for biomechanical (failure and inflation–extension) testing along with geometrical and histological evaluation. Results:The thoracic aorta presented increased strength longitudinally in propranolol-treated than untreated rats, resulting from increased adventitial collagen content. The distensibility of carotid artery increased in propranolol-treated rats at low-to-physiologic pressures, resulting from decreased medial collagen content. Structural remodeling was characterized by reduced lumen diameter, wall mass, and thickness-to-radius ratio. The latter, together with the greater resorption of the media than adventitia, related with the measured opening angle decrease in propranolol-treated rats. Conclusions:The geometrical/biomechanical remodeling was mediated by the hemodynamic effects of propranolol treatment, namely the reduced blood flow, and served to normalize in vivo hoop stresses as well as vessel compliance.
