Letter by Hartog et al Regarding Article, “Advanced Glycation End Products Accumulate in Vascular Smooth Muscle and Modify Vascular but Not Ventricular Properties in Elderly Hypertensive Canines”
To the Editor:
We read with great interest the article by Shapiro et al1 and would like to congratulate the authors on their important results. Advanced glycation end products (AGEs) are of interest in cardiovascular disease. Among others, they have been associated with the development of vascular and cardiac dysfunctions in both experimental animal and human studies.2,3 AGEs are a heterogeneous group of compounds. Several different AGEs exist; some show cross-linking properties, whereas others do not. In their study, Shapiro et al1 only measured tissue accumulation of the non–cross-linking AGE Nε-(carboxymethyl)lysine; they did not measure tissue accumulation of cross-linking AGEs, such as pentosidine. One major finding was that they did not detect Nε-(carboxymethyl)lysine in collagen-rich areas. On the basis of this finding, they concluded that the observed effects on vascular function may be mediated by mechanisms other than collagen cross linking. However, the authors cannot exclude the possibility that cross-linking AGEs are present in collagen-rich areas that might show an effect in response to ALT-711 treatment. Therefore, in our opinion, even after the results of this elegant study, it still remains unknown whether AGE cross linking or AGE receptor–mediated effects are more important in causing AGE-related vascular dysfunction.