Polyamines, vascular smooth muscle, and deoxycorticosterone acetate-salt hypertension.

This study was performed to determine if an alteration in vascular polyamine contents is associated with the development of deoxycorticosterone acetate-salt hypertension. The effects of chronic administration of alpha-difluoromethylornithine, a specific irreversible inhibitor of ornithine decarboxylase and thus polyamine biosynthesis, on vascular polyamine contents, structure, and function as well as the development of hypertension was studied. Control and deoxycorticosterone acetate-salt rats received either tap water or a drinking solution containing alpha-difluoromethylornithine for 6 weeks, during which period systolic blood pressures were recorded. Vascular reactivity studies were performed on rings of aorta and tail artery. Medial thickness, vessel weight, and vascular polyamine contents were also assessed in these arteries. alpha-difluoromethylornithine treatment had no significant effect on either systolic blood pressure or vascular structure, function, and polyamine contents of control animals. The elevation in blood pressure and the increase in medial thickness, ring weight, and vascular polyamine contents as well as altered vascular reactivity observed in deoxycorticosterone acetate-salt rats was significantly attenuated by alpha-difluoromethylornithine treatment. These results are the first to demonstrate that vascular polyamine contents are elevated in the deoxycorticosterone acetate-salt rat and that chronic alpha-difluoromethylornithine treatment prevents the rise in vascular polyamines as well as the elevation in blood pressure and attendant changes in the vasculature. Thus, the increase in vascular polyamines may comprise a critical link between the initiating stimuli and the alterations in vascular structure and function implicated in the pathogenesis of deoxycorticosterone acetate-salt hypertension.