Hypertension in normotensive and hypertensive rats by spermine ingestion

Polyamines (putrescine, spermidine and spermine) play an important role in the development of hypertension and in the expression of atrial natriuretic peptide (ANP), a cardiac hormone involved in the regulation of blood pressure. Wistar Kyoto normotensive (WKY) and spontaneously hypertensive rats (SHR) were given spermine in drinking water (0.5%) for 15 days. The spermine intake elevated the blood pressures of both SHR and WKY rats and reduced the expression of ANP (Northern blotting) in the ventricles. ANP levels in the plasma determined by enzyme immunoassay (EIA) showed no changes in the levels of plasma ANP after spermine intake. An analysis of polyamines by high-pressure liquid chromatography showed that the levels of spermine and spermidine were elevated in SHR hearts. It was in SHR hearts alone that spermine intake was associated with increases in the levels of putrescine. The results suggest that spermine-induced increases in blood pressure may involve mechanisms other than ANP.