Adrenoreceptor antagonist activity

Similar to dihydropyridine calcium blockers, many 0-adrenoreceptor antagonists exhibit antioxidant activity. Mak and Weglinski [290] showed that the pretreatment of canine myocytic sarcolemmal membranes with 0-adrenoreceptor antagonists (propranolol, pindolol, metoprolol, atenolol, or sotalol) (Figure 29.15) inhibited superoxide-induced sarcolemmal... 

The alpha-2-adrenoreceptor antagonist yohimbine increases adrenergic activity and may provoke anxiety and panic symptoms in patients but no or only mild symptoms in healthy volunteers. Yohimbine infusions evoke intrusive symptoms, i.e. flashbacks together with significant increase of... 

The production of reactive oxygen species (ROS) is associated with cytotoxicity. In the CNS, microglia are an important source of these species. In neonatal hamster microglia stimulated with phorbol myristate acetate, a PKC activator, isoproterenol reduces the production of superoxide anion and this decrease was blocked by a P-adrenoreceptors antagonist (Colton and Chernyshev, 1996). 

Prazosin is a selective competitive ai-adrenoreceptor antagonist widely used not only as a pharmacological tool for ai-adrenoreceptor subtypes characterization but also as an effective agent in the management of hypertension. Its antihypertensive activity depends on a peripheral vasodilatation mediated by a postjunctional aj-adrenoreceptor blockade. Moreover, given its high O]-selectivity, prazosin lacks side effects such as... 

Other intracorporal agents used to induce penile erections include papaverine, a drug with a relaxant effect on smooth muscle, and phentolamine, an a-adrenergic receptor blocker. Yohimbine, an a2-adrenoreceptor antagonist, enhances noradrenergic neurotransmission and may improve erectile dysfunction via adrenergic system activation. 

The drug is anon seleetive a-adrenoreceptor antagonist and the blockade caused is reversible. Besides, exhibiting a-bloeking activity it possesses a plethora of other pharmacological actions, namely ... 

Antagonistic action on the same target. For example, stimulation and blocking of beta adrenoreceptors, an activator and blocker of the potassium channel, etc. 

Several quinazoline derivatives have antihypertensive activity. Examples include prazosin 1163, doxazosin 1164, terazosin 1165, bunazosin 1166, and trimazosin 1167, which bind to Qj-adrenoreceptors, and ketanserin 1168, a serotonin 5-HT2 receptor antagonist. 

Astrocytes also express adrenoreceptors (Hertz et al., 1984) (Richards et al., 1989) and their activation has been shown to play some role in inflammatory contexts. NE reduces iNOS expression and nitrate accumulation in LPS plus cytokines-stimulated rat primaiy astrocytes (Feinstein et al., 1993 Feinstein, 1998). The reduction in the nitrate accumulation is attenuated by propranolol, but not by phentolamine, an a antagonist (Feinstein et al., 1993) (Facchinetti et al., 2004). 

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