IC50: 0.44 μM
The contractile effects of adrenaline and noradrenaline may be mediated by both postjunctional α2- and α2-adrenoceptors on vascular smooth muscle. B-HT 933 is a selective α2-adrenoceptor agonist.
In vitro: B-HT 933, a selective α2-adrenoceptor agonist, contracts human subcutaneous resistance arteries by a mechanism largely dependent on the influx of extracellular Ca2+, probably through voltage-operated calcium channels. This action involves a pertussis toxin-sensitive G protein, possibly GQ [1].
In vivo: The dose-related effects of the selective α2-adrenoceptor agonist B-HT 933 on the body temperature of untreated and reserpine-treated mice were investigated. In untreated mice B-HT 933 induced a dose-related hypothermia. The highest dose of B-HT 933 elicited a marked hypothermia, whereas the maximal hypothermic effect of clonidine was less pronounced and reached a plateau at a dose of 0.5 mg/kg [2].
Clinical trial: Up to now, B-HT 933 is still in the preclinical development stage.
Reference:
[1] N. A. Parkinson & A.D. Hughes. The mechanism of action of 1c2-adrenoceptors in human isolated subcutaneous resistance arteries. British Journal of Pharmacology (1995) 115, 1463-1468
[2] D. J. Bill, I.E. Hughes & R.J. Stephens. The thermogenic actions of x2-adrenoceptor agonists in reserpinized mice are mediated via a central postsynaptic ac2-adrenoceptor mechanism. Br. J. Pharmacol. (1989), 96, 133-143