M.A. Muros

Morphometric data on the arterial duct in the human fetal heart

In a total of 496 fetuses and newborns ranging in body weight from 60 to 5000 g, we performed a morphometric study of the ascending aorta, the descending aorta, the aortic isthmus, the right pulmonary artery, the left pulmonary artery and the arterial duct. In all, nine different parameters were measured in each specimen. The variations in the correlations between two measurable characteristics, namely body weight and each of the morphometric parameters, were analyzed. The minimum, normal and maximum patterns of normality for each parameter were obtained with regression equations. We compared statistically the diameter of the arterial duct with the diameter of the ascending and descending aorta, the aortic isthmus, the right pulmonary artery and the left pulmonary artery with one way analysis of variance, using Bonferronis test in the pairwise comparisons. The diameter of the arterial duct was smaller than the diameter of the ascending and descending aortas, the aortic isthmus, the right pulmonary artery and the left pulmonary artery, and the diameter of the ascending aorta was larger than that of the descending aorta. These morphological data have immediate clinical and surgical applications in the treatment of fetal and perinatal cardiovascular disorders.

Influence of fibric acid derivatives on intermediate filament proteins in myocardiocyte cultures

We analyzed desmin and vimentin accumulation in chick myocardiocyte cultures treated with the fibric acid derivatives bezafibrate, fenofibrate and gemfibrozil. The most noteworthy finding was the 50% decrease in the cytoplasmic desmin fraction in cells treated with gemfibrozil in comparison to control cultures, and the 19% increase in the cytoskeletal fraction in cultures treated with gemfibrozil and with bezafibrate. Vimentin accumulation by cells treated with bezafibrate was similar to that in control cultures, however the cytoskeletal vimentin fraction rose by 26% after treatment with gemfibrozil, and fell 13% after treatment with fenofibrate. No vimentin was found in the cytoplasmic fraction of cell treated with bezafibrate. Given the role of intermediate filaments in heart muscle contraction, fibric acid derivative- induced changes in the cytoplasmic and cytoskeletal concentrations of intermediate filament proteins may be related with the secondary effects of these drugs on heart rate.

Modulation of contractile proteins in embryonic and fetal chick cardiac cells by phorbol ester, gamma-interferon, 5-azacytidine and diacylglycerols.

We studied changes in the concentration of tropomyosin, actin, desmin and vimentin in cultured myocardiocytes from Hamburger and Hamiltons stages 29 and 39 chick embryos (HH29 and HH39) (1), treated with 12-o-tetradecanoyl-phorbol-13-acetate (TPA), 5-azacytidine (AZA), gamma interferon (INF) and diacylglycerols (DAG). In embryonic myocardiocytes at HH29, the first three agents modified the intracellular distribution of the thin filament proteins tropomyosin and actin, increasing their cytoplasmic concentration and decreasing their cytoskeletal concentration. The concentration of the intermediate filament proteins desmin and vimentin increased in both subcellular fractions after treatment with these drugs. In fetal myocardiocytes at HH39, total protein content decreased after treatment with these drugs. Cytoplasmic and cytoskeletal concentrations of actin and tropomyosin decreased to different degrees after treatment with TPA, AZA or DAG in HH39 myocardiocytes. TPA, AZA and DAG decreased desmin in the cytoplasmic and cytoskeletal fractions. These findings suggest that the drugs tested alter the normal protein composition in cultured myocardiocytes, and have different effects depending on the developmental stage in which the embryo is treated.

Effects of fibric acid derivatives on accumulation of actin in myocardiocytes

We used sodium dodecylsulphate polyacrylamide gel electrophoresis and immunoblotting to analyze the effects of the fibric acid derivatives bezafibrate, fenofibrate and gemfibrozil on the accumulation of actin in the cytoplasmic and cytoskeletal fraction of cultured myocardiocytes. All three drugs tested modified cellular and subcellular actin in different ways, and the findings are thought to be related with the secondary effect of arrhythmia known to be caused by these drugs. Bezafibrate and gemfibrozil more markedly affected accumulation of actin by myocytes, while fenofibrate interfered less notably with the accumulation of this protein.

Changes in tropomyosin during primary culture of embryonic myocardiocytes

We chose the Hamburger and Hamiltons stage 29 (HH 29) to investigate the expression of tropomyosin in chick myocardiocytes during 14 days on culture. Throughout 14 days of cell culture, changes in cell morphology were accompanied by a redistribution of tropomyosin in different cell compartments. We used FACScan, SDS-PAGE and densitometric analysis to quantify total cell tropomyosin and concentrations of this protein in different cell fractions. Tropomyosin was found mostly in the cytoskeletal fraction than in the cytoplasmic. When we compared the densitometric values from SDS-PAGE of cells in different stages of development we found that in HH 19, tropomyosin was more abundant in the cytoplasmic than in the cytoskeletal fraction. By HH 29, the two fractions had become inverted, and in HH 39, tropomyosin was clearly more abundant in the cytoskeletal than in the cytoplasmic fraction. In the IFI analysis, tropomyosin was found to label the Stress fiber-like structures (SFL) in different patterns depending on the area of the cell which expressed this protein.