Rapid determination of desmosine and isodesmosine in tissue hydrolysates by isocratic high performance liquid chromatography and precolumn derivatization

Hyperhomocysteinemia induces elastolysis in minipig arteries: structural consequences, arterial site specificity and effect of captopril-hydrochlorothiazide

Hyperhomocysteinemia is a risk factor for arterial diseases, and the deterioration of the arterial elastic structures is one of the possible mechanisms underlying this epidemiological association. The aim of this paper is to quantitatively characterize such structural alterations and to explore their causes in a previous model of dietary induced mild hyperhomocysteinemia in minipigs. After four months, both a morphodensitometrical analysis of the elastic structure and a biochemical analysis of elastin and elastase activities were performed on the infrarenal abdominal aorta (IRAA) and the proximal left interventricular coronary artery (LIVCA) of control (C), hyperhomocysteinemic (H) and captopril-hydrochlorothiazide (Cp-Htz, 25 + 12.5 mg/d)-treated (H+/-Cp) minipigs (n = 8/group). Hyperhomocysteinemia was found to induce an increase in parietal elastolytic metalloproteinase activities. It resulted in opening and enlargement of fenestrae through the medial elastic laminae and in a decrease in medial elastin content (p < 10(-3)), expressed as well as volume density (%) as weight concentration (microg elastin/mg dry tissue). The thickness of the media and its basic lamellar organization was unchanged. The reduction in volume density was more dramatic in LIVCA (H: 4.7 +/- 0.9 vs C: 8.8 +/- 2.4), where it was evenly distributed within the media, than in IRAA (H: 6.7 +/- 1.1 vs C: 9.3 +/- 1.2), where the deep medial layers were less affected. Cp-Htz partly prevented the hyperhomocysteinemia-induced reduction of the medial elastin content in LIVCA (5.7 +/- 1.2) and IRAA (7.9 +/- 1.4). This effect, occurring in the subintimal layers of the media in both arteries but not in the deeper layers, resulted in a less beneficial effect in LIVCA than in IRAA. This result parallels the moderate beneficial therapeutic effect of ACE inhibitors against coronary atherosclerosis in humans. This paper reports for the first time a quantitative analysis of the arterial site-dependent deterioration of the elastic structure caused by mild hyperhomocysteinemia and the involvement of metalloproteinases in this process. These results confirm that the plaque-independent damage to elastic structure previously described in hyperhomocysteinemic-atherosclerotic minipigs was mainly due to homocysteine. This highlights that the metalloproteinase-related elastolysis and the subsequent structural deterioration is one of the major events underlying the epidemiological association between mild hyperhomocysteinemia and arterial diseases.

Therapeutic effects of nitric oxide-donor isosorbide dinitrate on atherosclerosis-induced alterations in hemodynamics and arterial viscoelasticity are independent of the wall elastic component

Whether the arterial elastic structures are involved in the beneficial effects of long-term treatment with organic nitrates on atherosclerosis-induced changes in hemodynamics and arterial wall viscoelastic properties, are case for angiotensin-converting enzyme (ACE) inhibitors, is not known. In the present study, atherogenic (A) diet, and isosorbide dinitrate (ISDN) (I) (60 mg Risordan LP, daily dose) were given concomitantly for 4 months to adult Pitman-Moore minipigs (A + I animals, n = 8), which were compared with A (n = 8) or control (C, n = 8) animals. Blood flow was investigated by hemodynamics in the hindlimb arterial bed; and wall rheology, histomorphometry and elastin; and desmosine (DES) and isodesmosine (IDE) contents in the abdominal aorta. Atherosclerosis prominently impaired the function of capacitance and resistance arteries, altered blood pressure contours, increased aortic stiffness and wall tension, and reduced parietal viscoelasticity through viscous component blunting. The treatment with ISDN significantly improved aortic pulsatility, arteriolar opposition to blood flow, and blood pressure (BP) contours by restoring, at least in part, the wall viscoelastic properties. However, there was no significant change in the area of the pressure-diameter curve hysteresis between the three animal groups. In contrast, ISDN reduced neither the cross-sectional area of lesions nor the losses in wall elastin content and had no influence on lipid accumulations in vessels and in the blood. The present results demonstrate that the beneficial hemodynamic and wall viscoelastic effects elicited by ISDN in atherosclerotic minipigs are not accounted for by therapeutic properties of the nitric oxide (NO) donor against alterations of elastic structures, but by the viscoelastic properties in the arterial wall.