Concomitant up-regulation of insulin binding and elevated heat sensitivity in serum depleted CHO cells

When HA-1 CHO cells were cultured in media with a range of fetal calf serum (FCS) concentrations, they became increasingly heat sensitive at low (5%) serum levels. Heat sensitization occurred concomitantly with increased insulin binding capacity. Insulin binding capacity also became more heat sensitive. Thermotolerance induced by a mild treatment (10 min/45 degrees C) 12 hr prior to assay, caused marked heat resistance expressed both as cell survival or insulin binding and abolished differences in sensitivity between the serum adapted cell lines.