BRL 37344, sodium salt is a potent and selective agonist of β3 adrenoceptor with Ki values of 287, 1750 and 1120 nM for β3, β1 and β2 receptors, respectively [1].

β3 adrenoceptor is exists mainly in adipose tissue and plays an important role in the regulation of thermogenesis and lipolysis.

BRL 37344, sodium salt is a potent and selective β3 adrenoceptor agonist. In isolated rat brown and white adipocytes, BRL 37344 significantly stimulated lipolysis with EC50 values of 5 and 56 nM in brown adipocytes and white adipocytes, respectively [1]. In the isolated guinea pig heart, BRL 37344 (10-8-10-5 M) increased heart contractility (dP/dt) and coronary flow (CF). However, BRL 37344 (10-8 M) completely inhibited isoprenaline-induced increase in contractility, which suggested that BRL 37344 display β1-antagonistic properties [2].

In fasted rabbits, BRL 37344 significantly increased plasma nonesterified fatty acids (NEFA) levels through β3-adrenoceptor. However, BRL 37344 had no effect on plasma glucose levels [3]. In mice, BRL 37344 increased circulating transaminase levels through activation of β3-adrenoceptor [4].

References:
[1]. Simard PM, Atgié C, Mauriège P, et al. Comparison of the lipolytic effects of norepinephrine and BRL 37344 in rat brown and white adipocytes. Obes Res, 1994, 2(5): 424-431.
[2]. Kozlovski VI, Chlopicki S, Gryglewski RJ. Effects of two beta3-agonists, CGP 12177A and BRL 37344, on coronary flow and contractility in isolated guinea pig heart. J Cardiovasc Pharmacol, 2003, 41(5): 706-713.
[3]. Reverte M, Rivas-Cabanero L. Effects of the beta 3-adrenoceptor agonist BRL 37344 on lipomobilization and plasma glucose levels in conscious fasted rabbits. Can J Physiol Pharmacol, 1996, 74(3): 251-256.
[4]. Kasahara H, Muto S, Motokawa Y, et al. β3-adrenoceptor-mediated increased circulating transaminase levels in mice treated with its agonist BRL 37344. J Toxicol Sci, 2010, 35(5): 779-784.