Prostacyclin production by cultured smooth muscle cells from atherosclerotic rabbit aorta.

Prostacyclin (PGI2) synthesis seems to be one of the major physiological mechanisms involved in regulating platelet and vessel wall interactions. PGI2 is produced in large amounts by vascular endothelial cells, and vascular smooth muscle cells (SMC) also produce significant quantities. The capacity of SMC to produce PGI2, especially after endothelial injury, seems to be of importance. It is probably this type of situaton that is involved in the atherosclerotic process: experimental atherosclerosis in rabbits has been associated with a severe decrease in PGI, synthesis by arteries. Lipid peroxide accumulation within the arterial wall or in the plasma may also be involved in this process. Using arterial SMC in culture, we demonstrate here that, in comparison with healthy cultured cells, cells originating from atherosclerotic aorta have a decreased capacity to produce PGI2. The results were obtained using biological and radiochemical techniques and were confirmed by GC-MS. They suggest a potential role for PGI2 in inhibiting the atherosclerotic process.

[Biosynthesis in vitro of extracellular matrix in arteriosclerotic areas of rabbit aortas. Autoradiographic study of tritiated proline incorporation kinetics]. / Biosynthèse de la matrice extracellulaire dans les aires athéroscléreuses d'aortes de lapins in vitro. Etude autoradiographique de la cinétique d'incorporation de proline tritiée.

The elaboration of the extracellular matrix was investigated by radio-autoradiography after incubation of aortic strips, isolated from thoracic aortas of healthy and atherosclerotic rabbits, with tritium labeled proline. Time course experiments indicated that there was a delay of about one hour before significant amounts (25%) of tritiated macromolecules were released from the intact smooth muscle cells. On the contrary, both, the level of incorporation and the rate of excretion of macromolecular components by modified smooth muscle cells of the atherosclerotic area from injured strips were increased. The results indicate that, under the conditions of incubation in vitro, the modified smooth muscle cells of atherosclerotic plaque exhibit a particular behaviour for both, quantitative and qualitative features of macro-molecular synthesis of the extracellular matrix.

Fibrous long spacing collagen in aortic explants of normal rabbit cultured in hypercholesterolemic serum.

Aortic tissues consisting of all three tunics were removed from normal adult rabbits and cultured in a semisynthetic gelosed medium supplemented by 10% serum obtained either from normal or hypercholesterolemic rabbits. Fibrillar cross-striated aggregates appeared with a high frequency (50%) in the extracellular space of explants cultured from four to eight days in medium supplemented by serum from hypercholesterolemic rabbits, but did not appear in explants cultured in serum from control animals (3%). The electron-dense segment was ruthenium red positive and digested by testicular hyaluronidase. The electron-lucent segment, composed of ruthenium red negative thin filaments, was not modified after hyaluronidase treatment but was strongly digested after collagenase treatment. It is believed that this material was fibrous long spacing collagen synthetized under culture conditions, as shown after tritiated proline incorporation.