Effects of deoxycorticosterone/salt hypertension on cell ploidy in rat aortic smooth muscle cells
Chobanian, A.V.; Lichtenstein, A.H.; Schwartz, J.H.; Hanspal, J.; Brecher, P.
Circulation 75(1 Part 2): I102-I106
1987
ISSN/ISBN: 0009-7322 PMID: 3791614 Document Number: 305099
The effect of hypertension on DNA content of isolated aortic smooth muscle cells and their nuclei has been studied in Wistar rats treated with deoxycorticosterone and salt (DOC/salt). Eight weeks of DOC/salt administration induced a significant increase in aortic smooth muscle cells with tetraploid nuclei from 9.7 +/- 0.8% (mean +/- SE) in control animals to 26.6 +/- 2.4% with DOC/salt. The tetraploid cells appeared approximately 60% larger in size than diploid cells as estimated by forward light scatter. Prolonged reversal of hypertension by withdrawal of DOC/salt for 3 months did not reduce nuclear tetraploidy significantly but appeared to prevent further increases. The results suggest that hypertension influences the growth cycle of aortic smooth muscle cells and increases nuclear polyploidy and cellular hypertrophy. Preliminary studies have also been performed to measure transmembrane potential in isolated viable aortic smooth muscle cells with a lipophilic cationic fluoroprobe, 3,3 dipentyloxacarbocyanine, which distributes into cells in a potential-dependent manner. Norepinephrine (10(-6)M to 10(-3)M) appeared to produce a concentration-dependent reduction in membrane potential that was blocked by equimolar concentrations of prazosin but not of yohimbine. The studies suggest that norepinephrine can cause depolarization of smooth muscle cells through an alpha 1-mediated mechanism.