AT RECEPTOR INHIBITION AFFECTS THE NORADRENALINE SENSITIVITY IN ISOLATED PORTAL VEIN OF NORMOTENSIVE RAT

Abstract

Short term treatments of normotensive Wistar Kyoto rats with angiotensin II (ANGII) or in combination with the AT₁ receptor antagonist, losartan or PD123319, the AT₂ receptor antagonist on systemic arterial blood pressure (MABP) and their influence on noradrenaline sensitivity in isolated mesenteric portal vein were evaluated. ANGII increased MABP as well as the contractile response to noradrenaline in vessels from ANGII-treated animals. MABP and the maximal effect of the concentration response curve for noradrenaline were prevented by losartan. However, PD123319 did not influence the blood pressure, but completely removed the vessels sensitivity to noradrenaline. ANGII combined with the AT₁ and/or AT₂ receptors blockade completely prevented the pressure response to ANGII, but the concentration response curve for noradrenaline did not differ from the vehicle-treated control curve. In conclusion both AT₁- and AT₂ receptor activation seems to be important in controlling noradrenaline sensitivity of rat portal vein smooth muscle.

• Angiotensin II
• AT receptors antagonists
• Noradrenaline
• Isolated portal vein
• Normotensive rats