Pharmacological properties of β-adrenoceptors mediating rat superior mesenteric artery relaxation and the effects of chemical sympathetic denervation.

Aims: β-Adrenoceptors (β-ADRs) mediating the relaxation of rat superior mesenteric arteries (SMAs) were pharmacologically identified, and the effects of chemical sympathetic denervation on β-ADR-mediated relaxation were examined.

Main Methods: The tension changes of endothelium-denuded SMAs were isometrically recorded and the mRNA of endothelium-denuded SMA β-ADR was detected using RT-PCR.

Key Findings: In endothelium-denuded SMAs contracted with ≥10 M phenylephrine (an α-ADR agonist), isoprenaline (a β-ADR agonist)-induced relaxation was competitively inhibited by 3 × 10-10 M propranolol (a β-ADR antagonist), but not further affected by ≥10 M propranolol.