Age-related medial elastocalcinosis in arteries: mechanisms, animal models, and physiological consequences

Abstract

Atkinson J. Age-related medial elastocalcinosis in arteries: mechanisms, animal models, and physiological consequences. J Appl Physiol 105: 1643-1651, 2008. First published September 4, 2008 doi:10.1152/japplphysiol.90476.2008.-With age, the calcium content of the arterial wall increases. Calcification occurs at two main levels: intimal plaques and the medial elastic fiber network. The latter has been referred to as medial elastocalcinosis and is the subject of this review. The mechanisms involved in elastocalcinosis are complex and involve polar, apolar, and active processes. Vascular calcification may be species specific to humans. As laboratory animals, such as the rat, grow old, they suffer from only very mild arterial calcification. Different animal models of induction of massive arterial calcification by pharmacological and other means exist. Although extrapolation from such models to the clinical situation in terms of etiology is difficult, such models could be useful in the nonclinical study of the pathophysiological consequences of vascular calcification. Vascular calcification modifies arterial wall stiffness, and this could have clinically significant consequences on cardiac function and downstream circulatory control.artery; calcium; wall stiffness; aging Development of the Concept of ElastocalcinosisSeveral recent reviews deal with the subject of elastocalcinosis (1,21,25,41,54,56,82,108).Age-linked vascular calcification has been known since the nineteenth century (85,122). It appears to be "specific" in that vascular wall calcium and phosphorus contents increase with age, whereas there are no significant increases in the aortic content of most other elements, such as sodium, potassium, and magnesium (128). Vascular calcification linked to age is also specific for arteries and does not involve other soft tissues, such as veins (57,60,117). Vascular calcification is associated with hypertension. Blumenthal et al. (9) showed that the onset of arterial calcification occurs at an earlier age in hypertensive subjects. The association in humans between arterial calcification and hypertension has since been reported by many investigators (75). The etiology of the complex multifactorial interactions, however, between hypertension (and associated changes in vascular wall mechanics) and amplification of calcification remains obscure.Vascular calcification can occur in localized intimal plaques and in a diffuse fashion in the media (53), and often there is no indication in published reports of where samples were taken. Méndez and Tejada (76) reported that the calcium content of plaques is 10-fold higher than that of "plaque-free" artery. Thus "contamination" of samples with plaque material could mask medial, diffuse elastocalcinosis. It is to be noted that the calcium content of "normal" intima (i.e., free of plaques and fatty streaks) is low and shows only a slight increase with age (6, 29). Medial elastocalcinosis independent of atheroma-associated calcification has been demonstrated by Elliot and McGra...

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