Atipamezole Hcl(MPV1248 Hcl) is an alpha-adrenoceptor antagonist with high affinity and selectivity for the alpha 2-receptor.
IC50 value:
Target: alpha2-adrenoceptor antagonist
in vitro: The alpha2-adrenoceptor antagonist atipamezole was a potent inhibitor of aldosterone release (range 10-1000 nM) [1].  In receptor binding studies [( 3H]-clonidine and [3H]-prazosin displacement) an alpha 2/alpha 1 selectivity ratio of 8526 was obtained for atipamezole, while idazoxan and yohimbine showed ratios of 27 and 40, respectively. Atipamezole had also about a 100 times higher affinity on alpha 2-adrenoceptors than the reference compounds [3].
in vivo: In vivo studies of [3H]atipamezole demonstrated good penetration into the brain (0.3-1.8% injected dose/g at 5 min, depending upon brain region). In addition, [3H]atipamezole displayed rapid in vivo clearance of nonspecific binding such that at 1 h following an i.v. injection of the drug (100 microCi/animal, rat tail vein administration) the pattern of radioactivity in the brain correlated very well with the receptor distribution as seen by in vitro autoradiography [2]. In mice, medetomidine-induced sedation was effectively antagonized by atipamezole   

((plusmn))-Bisoprolol hemifumarate  Bisoprolol is a selective type β1 adrenergic receptor blocker.

Target: Adrenergic Receptor
Approved: July 31, 1992
Bisoprolol, on beta 1-adrenoceptor peptide induced autoimmune myocardial damage. In the animal model of autoimmune cardiomyopathy induced by active immunization of rabbits with beta 1-adrenoceptor peptide, bisoprolol was given at a dose of 3 mg/day throughout the study period. Our results showed high titer of anti-beta 1-adrenoceptor antibody in the immunized group throughout the study but not in the group receiving only bisoprolol [1]. Bisoprolol administration resulted in a significant reduction in HR reaching 60.3 +/- 1.4 bpm at VT of 500 mL (compared to 70.5 +/- 1.8 bpm with placebo, P < 0.001). Changes in HP were also significant with an increase in HP reaching 1004.5 +/- 22.2 msec at this controlled VT (compared to 860.3 +/- 21.5 msec with placebo, P < 0.001) [2].
Toxicity: Oral, mouse: LD50 = 100 mg/kg; Skin, rabbit: LD50 = 200 mg/kg; Skin, rat: LD50 = 500 mg/kg. Symptoms of overdose include congestive heart failure (marked by sudden weight gain, swelling of the legs, feet, and ankles, fatigue, and shortness of breath), difficult or labored breathing, low blood pressure, low blood sugar, and slow heartbeat.