Alterations of vascular prostacyclin and thromboxane A2 in Dahl genetical strain susceptible to salt-induced hypertension

To assess the implications of vascular eicosanoids system in the hypertension of Dahl salt-sensitive (Dahl S) strain, we investigated the production of vascular vasodepressor and vasoconstrictor eicosanoids in Dahl S rats. 14-week-old Dahl S rats on a 0.11% NaCl diet (normotension) or a 0.3% NaCl diet (borderline hypertension) had a significantly lowered generation of vascular prostacyclin (PGI₂), compared with Dahl salt-resistant (Dahl R) rats. The impairment of vascular PGI₂ in Dahl S rats was restored to the normal level of Dahl R rats with the elevation of blood pressure induced by a high salt diet (4% NaCl). The production of vascular PGI₂ was closely related to the height of blood pressure. The deterioration of vascular PGI₂ was also found in 4-week-old Dahl S rats with normotension. Conversely, vascular thromboxane A₂ (TXA₂) was significantly enhanced in 14-week-old Dahl S rats in all of the feeding groups. Thus, it seems possible that the proved alterations of the vasodepressor and vasoconstrictor eicosanoids partially contribute to the genesis of salt hypertension. Although the exact mechanisms remain obscure, the adaptation of vascular PGI₂ on a high salt diet may be suitable to compete with the high blood pressure and to protect against the vascular damage.