Table 5.

Effects of GH and oleic acid on accumulation of newly synthesized apoB-48 and apoB-100 in medium, apoB mRNA editing, and total cellular protein labeling

GroupApoB-48 (%control)ApoB-100 (%control)Proportion of ApoB-48 (%total apoB)ApoB mRNA Editing (%edited)Total Protein Labeling (%control)
Control100 ± 12.5 100 ± 6.5* 47.0 ± 3.7 47.5 ± 0.7§ 100 ± 8.3
GH119 ± 15.5 60 ± 8.5 63.8 ± 3.2 56.2 ± 1.2 118 ± 26.6*
OA142 ± 6.8* 70 ± 17 65.1 ± 2.6 51.8 ± 2.4 111 ± 11.3*
OA + GH131 ± 26.4* 51 ± 8.3§ 69.2 ± 4.3* 60.5 ± 2.9* 131 ± 12.5*
  • Values are means ± SD. After plating, all cell cultures were given 1 nM dexamethasone and 0.75% albumin. GH (100 ng/ml) was given the last 24 h and 500 μM oleic acid the last 3 days of culture. Cells were labeled for 2.5 h with a [35S]methionine-cysteine mix. Thereafter, cells were washed and cultured for another 4 h in a medium containing 10 mM unlabeled methionine. Amounts of labeled apoB-48 and apoB-100 were measured in the chase medium, and the proportion of apoB-48 was calculated as apoB-48/(apoB-48 + apoB-100). ApoB mRNA editing was measured with primer extension analysis as described in materials and methods. Total protein labeling was measured as radioactivity in TCA-precipitable [35S]-labeled protein in the cells. Results presented are pooled data from 2 different experiments with 4 culture dishes/group. Values with different superscripts are significantly different from each other (P < 0.05, two-way ANOVA followed by Student-Newman-Keuls test).