Cell-to-cell interaction prevents cell death in cultured neonatal rat ventricular myocytes

Objectives: Loss of cardiac cells and the anatomical or functional remodeli ng of intercellular coupling occur under several pathological conditions. W e have assessed the significance of intercellular coupling for cell death. Methods and Results: Ventricular cells obtained from 1 day old Wistar rats were cultured. Apoptosis was detected by nick-end labeling. Cells were plat ed at low and high cell density (3 X 10(4)/ml and 12 X 10(4)/ml, respective ly). Cultured myocytes died spontaneously by apoptosis in a time dependent manner. The increase of the apbptotic cell population in a culture with hig h cell density on day 4 (1+/-1.2%, n=4) was significantly lower than that i n a culture with low cell density (20+/-5.5%, n=4). The progression of apop tosis in the culture of low cell density was prevented in part after applic ation of the medium extract from the culture of high cell density; the apop totic cell population on day 6 decreased from 57+/-8.0%, (n=4) to 36+/-3.8% (n=4). Treatment of the cultured myocytes at high cell density with antise nse oligonucleotide for connexin43 (Cx43) for; 24 h bn day 2 resulted in a significant decrease in Cx43 expression as judged by Western blot, dye tran sfer and immunocytochemistry using mouse monoclonal antibody for Cx43. in a ssociation with the down-regulation of Cx43, the progress of apoptosis was accelerated; the apoptotic cell population on day 5 in the antisense-treate d cultures (27+/-5.7%, n=4) was significantly higher than the sense-treated cultures (5+/-1.1%, n=4). The effect of Cx43 antisense treatment to promot e apoptosis was not reversed by application of high cell-density culture me dium. Conclusions: These findings suggest that cell-cell communication thro ugh gap junction formation and some humoral factors play important roles in the survival of cultured myocytes. (C) 2000 Elsevier Science B.V. All righ ts reserved.