Interactions between vascular endothelial (EC) and smooth muscle cells (SMC) contribute both to the normal function of the vascular wall and to the pathogenesis of lesions such as atherosclerosis and fibrointimal hyperplasia. However, study of these interactions has been hampered by the difficulty in growing these two cell types in simultaneous culture. Methods using conditioned media, shared media, and bilayer culture have been described, but none is well suited to the study of vascular cell interactions. We report a method for EC-SMC co-culture that preserves bilayer morphology, allows independent study of the cells and their matrices after intervention, remains stable over long periods in culture, and permits study of changes in cell-cell interaction with growth of the cells to confluence. This simple bilayer co-culture system simulates the in vivo situation and may enhance our understanding of EC-SMC interactions.

To study the interaction of endothelial and smooth muscle cells, and the means by which such interaction may affect lipid permeability of the arterial wall, cell bilayers were established by use of a transwell culture system. After confluent growth of both cell types had been achieved, iodine 125 bound to low-density lipoprotein (10 ng protein/ml) was added to the media of the upper well. After a 3-hour incubation period, the iodine 125-bound low-density lipoprotein content of the upper and lower media demonstrated an impedance to lipoprotein movement across the endothelial cell monolayer as compared to the bare porous polycarbonate filter of the transwell (p less than 10(-6)). The presence of smooth muscle cells in the bottom well significantly enhanced the permeability of the endothelial cell layer (p less than 10(-60). This effect remained unchanged over a 9-day time course. Membrane binding and cellular uptake of low-density lipoprotein by endothelial cells was not altered by smooth muscle cells, indicating that this change in permeability could not be easily attributed to changes in receptor-mediated transport or transcytosis. Membrane binding (p less than 0.02) and cellular uptake (p less than 10(-6)) of low-density lipoprotein by smooth muscle cells in the bilayer, when adjusted for counts available in the smooth muscle cell media, were both reduced in the early incubation period as compared to isolated smooth muscle cells. The disproportionate reduction in uptake as compared to binding would suggest that this was not entirely a receptor-dependent process.(ABSTRACT TRUNCATED AT 250 WORDS)

ABSTRACT:The aim of this study was to evaluate the effect of aerobic training (16 weeks -T1 and 24 weeks -T2) on oxidative stress biomarkers. To this end, GSH, GSH-peroxidase (GSH-Px) and catalase (CAT) activity were analysed in plasma. Nine bulls (3-4 years), were included in this work. The exercise training protocol was performed in a track ("taurodromo") three days per week for 24 weeks and consisted of 400 m warming up, 1200 m to 4-5 m/s, two minutes' resting, 1200 m to 4-5 m/s and, finally, 400 m walking. The results reflected that GSH-Px activity was higher at T1 (6.18 ± 0.45) than at baseline (T0; 2.31 ± 0.08) while the GSH level (2.98 ± 0.37) was lower vs. T0 (14.59 ± 3.40). Moreover, there were significant increases in GSH-Px (18.23 ± 1.36) and CAT (2.52 ± 0.04) activities and the recovery of basal values in GSH (11.75 ± 2.84) in T2. In conclusion, the type of training carried out in this study involved two well-defined stages: (i) a period of perturbation, followed by (ii) adaptation. The former stage was characterised by the induction of oxidative stress manifested as a decrease in the GSH, and the latter (T2) by the recovery of this non-enzymatic antioxidant.

Calcium channel blockade has been shown to inhibit experimental atherosclerosis in cholesterol-fed animals, and early clinical trials suggest its benefit in human subjects as well. Methods: To determine the effect of the calcium channel blocker nifedipine on lipid and monocyte infiltration of the subendothelial space, an endothelial cell (EC)-smooth muscle cell (SMC) brayer model of the arterial wall was incubated for 18 hours with nifedipine (0.1 ~g/ml). Iodine 125-labeled low-density lipoprotein (12SI-LDL) (10 ~g protein/ml) was then added to the upper-well medium. Results: After a 3-hour incubation period, nifedipine-treated bilayers showed an increased permeability to LDL (p < 10-7). Nffedipine had no effect on the membrane binding or cellular uptake of LDL by the EC but did increase SMC binding and uptake (p < 0.0005). U937 monocytes were found to incorporate 12sI-LDL in a concentration-dependent fashion, without saturation to 25 lzg/ml, the highest concentration studied. Nffedipine increased monocyte uptake of LDL (10 izg/ml; p < 0.003 but reduced monocyte movement through the EC barrier (p < 10-7). A study of the selective preincubation of each cell type (EC, SMC, and monocyte) with nifedipine indicated that this reduction was likely the result of a direct effect on the monocyte. Conclusions: Given the potential cytotoxic effects of the monocyte within the subendothelial space, nifedipine-induced inhibition of monocyte infiltration and enhancement of lipoprotein uptake by the SMC may be protective. (J VASC SURG 1993;17:841-8.) The observation that calcium and cholesterol content of the human aorta increases with age and calcium accumulation within the arterial intima precedes the development of atherosclerotic plaque led Blumethal et al. 1 postulate a putative role of calcium in atherosclerosis. Rosenblum et al.2 supported this hypothesis by demonstrating a direct correlation between elevated serum calcium levels and accelerated atherosclerosis in cholesterol-fed rabbits. Subsequently, the direct measurement of transcellular calcium flux allowed Strickberger et al. s to document an association between increased cyto-From the

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