Noradrenaline and angiotensin II modify vascular prostanoid release in fructose-fed hypertensive rats
A fructose-enriched diet induces hypertension, metabolic alterations and insulin resistance in rats, resembling human metabolic syndrome. Previously, we found that prostanoid production was altered in fructose-fed rats.
This study analysed the effects of incubation with noradrenaline (NA) and angiotensin II (Ang II) on prostanoid release in mesenteric vascular beds from control and fructose-fed rats. Animals which received fructose solution (10% w/v) for 22 weeks showed higher systolic blood pressure and triglyceridaemia.
In controls, NA increased 6-keto-prostaglandin (PG) F1α (prostacyclin metabolite) and thromboxane (TX) production. Ang II increased only TX release. In fructose-fed animals, NA increased 6-keto-PG F1α and TX. PGF2α (vasoconstrictor) was also elevated. Ang II also increased PGF2α and PGE2 levels.
In conclusion, in fructose rats Ang II in vitro stimulates a vasoconstrictor prostanoid not stimulated in controls. This could be related to the observed in vivo blood pressure increase. In fructose-fed animals, NA and Ang II also augment vasodilator prostanoids, suggesting a compensatory mechanism because of long-term hypertension.