B-HT 933 is an agonist of α2-adrenergic receptors (α2-ARs) with an EC50 value of 0.65 μM for contraction of canine sapheneous veins. It induces concentration-dependent inhibition of the twitch response in rat vas deferens and guinea pig ileum. B-HT 933 induces sedation and reduces motor activity in mice, an effect that is reversed by the α2-AR antagonist yohimbine . B-HT 933 decreases blood pressure and cardiac output in cats injected with 30 μg/kg intracisternally. It also exhibits antinociceptive effects in mice with ED50 values of 12.5, 20.5, and 6.1 mg/kg for the tail-immersion, tail-pinch, and acetic acid writhing tests, respectively.
B-HT 933 Dihydrochloride is a selective α2-adrenoceptor agonist and has less potent inhibitory effect on the sympathetic vasopressor responses in diabetic rats.
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].
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].
[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
