Effects of deoxycorticosterone-salt hypertension on cell ploidy in the rat aorta.

We investigated the effect of deoxycorticosterone-salt hypertension and its reversal on nuclear ploidy in rat aortic smooth muscle cells, using flow cytometry. Systolic blood pressure and the percentage of cells with tetraploid nuclei increased over a 4-week period and then remained constant. In control rats 6.0 +/- 0.6% of aortic cells had tetraploid nuclei, and this increased to 27.0 +/- 1.1 and 26.6 +/- 2.4% after 4 and 8 weeks of deoxycorticosterone-salt treatment, respectively. Computer analysis of the forward light scatter data obtained from the cell sorter indicated that the average tetraploid cell was approximately 1.6-fold larger than the average diploid cell in both normotensive and hypertensive animals. Analysis of the DNA content of intact cells and isolated nuclei indicated that the increased DNA content per cell was predominantly attributable to tetraploid nuclei rather than binucleated cells. Reversal of hypertension with either a low sodium diet for 8 to 13 weeks or chlorothiazide administration failed to reverse the abnormalities seen in arterial smooth muscle cell ploidy, despite normalization of the blood pressure and the ratio of heart to body weight.