Characterisation of the function of adult guinea-pig ventricular myocytes following co-culture with neonatal rat myocytes

Adult guinea-pig myocytes were co-cultured with a layer of spontaneously co ntracting neonatal rat myocytes based on a method described by Weisensee D. (In Vitro Cell Dev Biol 31: 190-195, 1995). Contractile studies were perfo rmed on freshly isolated, 24 and 48 h co-cultured adult guinea-pig myocytes to investigate whether alterations in contractile function had occurred. N o difference was found between freshly isolated and 24 h co-cultured adult guinea-pig myocytes in terms of sensitivity to calcium, isoprenaline, frequ ency response and beat duration. After 48 h, the frequency response was dep ressed (P < 0.02) and the beat was prolonged (P < 0.05) when compared to th at of freshly isolated myocytes. In the presence of the SR Ca2+ ATPase inhi bitor, thapsigargin, the beat was significantly prolonged (P = 0.003) in 24 h cocultured myocytes but not in freshly isolated myocytes. These findings show that adult guinea-pig myocytes can be maintained in co-culture with n eonatal rat myocytes with little change in contractile function for 24 h bu t after this time contractile function begins to deteriorate.