Smooth muscle cells of the media in the dilatative pathology of ascending thoracic aorta: morphology, immunoreactivity for osteopontin, matrix metalloproteinases, and their inhibitors.

The etiopathogenesis of thoracic aortic aneurysms is currently an issue of debate. The present study investigated ultrastructural, morphometric, and immunohistochemical aspects of smooth muscle cells (SMCs) in chronic aneurysm of the thoracic aorta (aneurysm group), aortic dilatation associated with valvular disease (valvular group), and dissection of the thoracic aorta (dissection group). Fragments of the ascending aorta that had been taken from the patients during coronary bypass surgery were used as controls. No significant difference was observed in the density of SMCs between the 3 pathologic groups put together and the controls. Only separate analysis of SMC density in each of the pathologic groups showed that the valvular group samples had significantly smaller amounts of SMCs in the internal layer of the media than the dissection group samples and controls. Ultrastructural analysis, in situ end labeling, propidium iodide assay, and DNA laddering did not show apoptosis of SMCs in the samples investigated. Ultrastructure of SMCs characteristic of the synthetic phenotype, together with increased expression of osteopontin in the media of pathologic thoracic aortas indicated the transition of SMCs from the contractile to the synthetic phenotype. Immunohistochemical investigation showed that medial SMCs in the samples taken from aortas of all 3 pathologic groups expressed stronger immunoreactivity for matrix metalloproteinase 1, 2, and 9 and tissue inhibitor of metalloproteinase 1 and 2 than the controls. The present study shows that during the formation of aneurysms, dissection of the thoracic aorta, or aortic dilatation associated with valvular disease, loss of SMCs was not of great importance with respect to their transition from the contractile to the synthetic type in leading to increased production of matrix metalloproteinases.

The role of long-chain acyl-CoA in the damage of oxidative phosphorylation in heart mitochondria.

The aim of this investigation was to study the effect of intramitochondrial acyl-CoA on the respiration of rabbit heart mitochondria over the whole range of stationary respiratory rates between States 4 and 3. The creatine phosphokinase system was used for stabilization of extramitochondrial adenine nucleotide concentration. It was shown that acyl-CoA depressed respiration more effectively in the intermediate range of respiration between States 4 and 3. The effect of acyl-CoA was negligible near State 4 and in State 3. These data are in line with our previous results concerning the dependence of the adenine nucleotide translocator control coefficient on the rate of mitochondrial respiration. Thus, our data suggest that long-chain acyl-CoA may regulate oxidative phosphorylation in heart mitochondria in vivo.

The role of adenine nucleotide translocators in regulation of oxidative phosphorylation in heart mitochondria.

The regulative role of adenine nucleotide translocators (ANTs) in oxidative phosphorylation has been estimated by the titration of respiration of isolated rabbit heart mitochondria with carboxyatractyloside in the presence of a non-rate limiting creatine phosphokinase ADP-regenerating system. It has been established that the respiration rate is not controlled by ANTs in the two extreme states, state 3 and state 4. On the other hand, at an intermediate respiration rate (30-70% of the state 3 respiration, which roughly corresponds to that under physiological conditions) the ANT control coefficient had a value of 0.62-0.75. Thus, ANTs seem to play a key role in the regulation of oxidative phosphorylation.