Figure 5

Insulin increases ribosomal content in cardiomyocytes. Cardiomyocytes (4 × 10⁶ cells per sample) were exposed to 50 mU/ml insulin or were left unstimulated. A, RNA was extracted from cardiomyocytes exposed to insulin for 1 h. Rps3 and Rps6 mRNA expression was measured by qPCR using the absolute quantification protocol. Results are expressed relative to unstimulated controls and are means ± SEM (n = 8 independent preparations of cardiomyocytes). * p < 0.05 relative to controls (Student's t-test). B, Protein extracts from cardiomyocytes exposed to insulin for 0, 2 or 4 h were immunoblotted with antibodies to Rps3 (upper panel) or Rps6 (center panel). * p < 0.05 relative to controls (Student's t-test). C and D, RNA was extracted and analysed for 18S and 28S ribosomal RNA content using an Agilent Bioanalyser. Representative traces are shown in panel C for unstimulated (Control) cells and cells exposed to insulin for 1 h. The areas under the 18S and 28S peaks were integrated and the results are shown in panel D as means ± SEM (n = 3 independent preparations of cardiomyocytes). * p < 0.05, # p < 0.01 relative to controls (one-way ANOVA with Tukey post-test).