Abstract
Abstract
To test whether cardiac muscle is a target for regulation by peptide growth factors, we analyzed the effects of two growth factors on actin and α-actinin expression at the subcellular level. Sodium dodecyl sulfate-gel electrophoresis, immuno-blotting, and fluorescense-activated cell sorter analysis were used to quantify the effects of basic fibroblast growth factor and platelet-derived growth factor on cultures of chick myocardiocytes during development. Cytoplasmic and cytoskeletal concentrations of actin and α-actinin were dependent on the stage of embryonic development and on the type of growth factor added to the culture. The most significant finding was the increase in actin and α-actinin expression in the cytoplasmic compartment after treatment with basic fibroblast growth factor of chick heart cells at Hamburger and Hamilton' stage 19. At stage 39, basic fibroblast growth factor induced less marked changes in the accumulation of actin and α-actinin. Platelet-derived growth factor decreased α-actinin expression slightly in the cytoskeletal compartment in more mature stages of heart development. Our findings support the hypothesis that basic fibroblast growth factor plays a role in cardiomyocyte differentiation during the early stages of development.
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