SR 59230A

B-Adrenoceptors belong to the family of G protein-coupled receptors. They are widely distributed throughout central and peripheral nervous systems and in peripheral tissues. The three subtypes of these receptors have been identified, B₁, B₂, and B₃. The B₃ receptor subtype is the predominant type found in adipose tissue. Activation of these receptors stimulates lipolysis in white adipose tissue while increasing energy expenditure in brown adipose tissue.

• Inhibits B₃ adrenoceptor agonist-induced inhibition of spontaneous motility in the rat isolated colon, with a pA₂ of 8.76¹
• Is 100 times less potent as an antagonist of B₁ or B₂ mediated responses to isoproterenol (I 5627) or salbutamol (S 5013) in guinea pig tissues²
• Blocks stimulation of cylic AMP synthesis in rat brown adipose tissue³
• Inhibits B₃ adrenoceptor-mediated relaxation in the human colon⁴
• Reduces the inhibition of colonic motility and the thermogenic response of brown adipose tissue elicited in rats by BRL 37344 (a B₃ selective receptor agonist, B-169) at oral doses²

References

1. Manara, L. et al., Br. J. Pharmacol., 117, 435-442 (1996).
2. Arch, J.R. and Kaumann, A.J., Med. Res. Rev., 13, 663-729 (1993).
3. Nisoli, E., et al., Mol. Pharmacol., 49, 7-14 (1996).
4. De Ponti, F., et al., Br. J. Pharmacol., 117, 1374-1376 (1996).