Effect of ploidy on transcription levels in cultured rat aortic smooth muscle cells.

Aging and hypertension increase the number of polyploid smooth muscle cells (SMC) in a blood vessel. We assessed the effect of ploidy on the transcription of several genes in SMC cultures derived from newborn and adult rats. In diploid and tetraploid subcultures of SMC from newborn rats, RNA expression of the genes assayed is linked with ploidy. However, when phenotypically different SMC cultures derived from newborn and adult rats were compared, transcription levels varied from gene to gene and not linked with the ploidy. Thus, differences in gene expression due to polyploidy are superimposed on those due to other phenotypical features.