Depletion of resistance vessel polyamines attenuates angiotensin II induced blood pressure rise in rats.

Vascular structural changes in hypertension are proposed to contribute to raised peripheral resistance. Endogenous polyamines (putrescine, spermidine and spermine) have an essential role in cellular growth and may be required in vascular restructuring. We have previously shown raised polyamines in resistance vessels in response to angiotensin II (angII) infusion in the rat and here we examined whether polyamine depletion influences the hypertensive process. Wistar-Kyoto rats were infused with either angII or saline by osmotic minipump, and maintained on either 2% difluoromethylornithine (DFMO; polyamine synthesis inhibitor) or water for 12 days. AngII significantly increased tail-cuff blood pressure (bp), resistance vessel spermidine and spermine concentration, and media:lumen ratios. DFMO attenuated both the rise in bp (p < 0.05) and vascular spermidine (p < 0.05) in the angII infused rats but vascular structure was apparently unaffected on day 12. In conclusion, raised concentration of resistance vessel spermidine may be a necessary component of the ang II pressor effect.