Atipamezole, an imidazoline-type alpha(2)-adrenoceptor inhibitor, binds to human platelets and inhibits their adrenaline-induced aggregation more effectively than yohimbine.

  title={Atipamezole, an imidazoline-type alpha(2)-adrenoceptor inhibitor, binds to human platelets and inhibits their adrenaline-induced aggregation more effectively than yohimbine.},
  author={P Mustonen and Juha Matti Savola and Riitta Lassila},
  journal={Thrombosis research},
  volume={99 3},
To investigate the usefulness of atipamezole [MPV-1248, 4-(2-ethyl-2, 3-dihydro-1H-inden-2-yl)-1H-imidazole], a novel alpha(2)-adrenoceptor-specific antagonist, as a tool in platelet studies, the ability of this antagonist: (1) to bind to platelet alpha(2)-adrenoceptors, and (2) to inhibit adrenaline-induced platelet aggregation was compared to that of yohimbine, another commonly used alpha(2)-adrenoceptor antagonist. It was found that atipamezole binds to platelet alpha(2)-adrenoceptors more… Expand
Identification and characterization of platelet α2-adrenoceptors and imidazoline receptors in rats, rabbits, cats, dogs, cattle, and horses.
Saturation binding studies in the presence of norepinephrine showed that Il-receptors may belong to a G protein-coupled receptor superfamily in canine platelets, and interspecific variations of platelet α2-adrenoceptor and imidazoline receptor expressions may explain different platelet responses to catecholamines and imdazoline α- adrenergic agents. Expand
Hypotensive and Antiaggregative Effects of Eugenosedin-B With Serotonin and α/β-Adrenoceptor Antagonistic Activities in Rats and Human Platelets
It is concluded that hypotensive and vasorelaxant effects of eugenosedin-B can be attributed to its multiple actions on the blockade of 5-HT1B,5-HT2A, α1/2 and β1 receptors, and its ability to reduce platelet aggregation attributed toIts blockade of α2 and 5- HT2A receptors. Expand
Blockade of platelet alpha2B-adrenergic receptors: a novel antiaggregant mechanism.
The results reveal that contrary to previous knowledge, the α2B-AR subtype does exist in platelets and is an important regulator of aggregation and may offer a novel therapeutic opportunity in the prevention of atherothrombotic events. Expand
Experimental Approach to Differentiation of the Effects Mediated by Imidazole Receptors and α2-Adrenoceptors on Platelets
We studied parameters of specific binding for various ligands of imidazole receptors and α2-adrenoceptors on human platelets. Pharmacological activity of compounds was evaluated by their effects onExpand
Platelets in nonresponders to epinephrine stimulation showed reduced response to ADP.
There is an impaired platelet responsiveness to ADP as well as to Epi in NR, due to a difference in downstream of the signal transduction pathway but independent of adenylyl cyclase inhibition. Expand
Antiplatelet Effect of Lonchocarpin and Derricin Isolated from Lonchocarpus sericeus.
Abstract In this work, we studied the effects of lonchocarpin (LCC) and derricin (DRC), two chalcones isolated from the hexane fraction of roots from Lonchocarpus sericeus. (Poir.) Kunth (Fabaceae),Expand
Structure–activity relationships of isoeugenol‐based chlorophenylpiperazine derivatives on serotonergic/adrenergic receptor, platelet aggregation, and lipid peroxidation
Three isoeugenol‐based eugenosedin chlorphenylpiperazine derivatives, Eu‐A, Eu‐B, and Eu‐C, were synthesized and tested for their serotonergic, adrenergic antagonist, antioxidant, andExpand
The Operculina macrocarpa (l.) urb. (jalapa) tincture modulates human blood platelet aggregation.
The tincture of Operculina macrocarpa has antiplatelet effect that cannot be attributed to a single biochemical mechanism and at least part of it cannot be related to the OMT inhibition of P2Y12 purinergic receptors. Expand
Analysis of platelet α2-adrenergic receptor activity in stable coronary artery disease patients on dual antiplatelet therapy
Combined antiplatelet therapy reduces recurrent atherothrombotic events in stable coronary disease patients; however, high residual platelet reactivity measured ex vivo still raises concerns as aExpand
Protective effect of dexmedetomidine against myocardial ischemia-reperfusion injury in rabbits.
PURPOSE To investigate the influence of dexmedetomidine on myocardial ischemia-reperfusion injury (IRI) in rabbits. METHODS Twenty-four New Zealand white rabbits were randomly divided into twoExpand


Characterization of [3H]atipamezole as a radioligand for α2-adrenoceptors
Atipamezole (MPV-1248, 4-(2-ethyl-2,3-dihydro-1H-inden-2-yl)-1H-imidazole), a potent alpha 2-adrenoceptor antagonist, was tritiated to high specific activity. We then compared [3H]atipamezole andExpand
Highly selective and specific antagonism of central and peripheral alpha 2-adrenoceptors by atipamezole.
The results show that atipamezole is a potent, selective and specific antagonist of both centrally and peripherally located alpha 2-adrenoceptors. Expand
Characterization of the selectivity, specificity and potency of medetomidine as an alpha 2-adrenoceptor agonist.
Based on results, medetomidine can be classified as a potent, selective and specific alpha 2-adrenoceptor agonist. Expand
Recombinant human alpha 2-adrenoceptor subtypes: comparison of [3H]rauwolscine, [3H]atipamezole and [3H]RX821002 as radioligands.
Kinetic, saturation and competition binding assays were employed to optimize and validate radioligand binding methods for characterization of recombinant human alpha 2-adrenoceptor subtypes and forExpand
Effects of Imidazoline and Non-Imidazoline α-Adrenergic Agents on Canine Platelet Aggregation
Aggregatory and antiaggregatory effects of imidazol(in)e and non-imidazol(in)e α-adrenergic agents on canine platelets were examined turbidimetrically in citrated platelet-rich plasma or washedExpand
Characterization of α2-adrenergic receptors on human platelets using [3H]yohimbine
Summary In order to investigate properties of alpha-adrenergic receptors of human platelets, we have examined the binding of [ 3 H]yohimbine, a potent α 2 -adrenergic 3 antagonist, to intactExpand
Alpha-2A and alpha-2B adrenergic receptor subtypes: antagonist binding in tissues and cell lines containing only one subtype.
Two distinct pharmacological profiles for the two alpha-2 adrenergic receptor subtypes in several different tissues are demonstrated, further support the existence and definition of these subtypes. Expand
Central alpha 2-adrenoceptors are highly stereoselective for dexmedetomidine, the dextro enantiomer of medetomidine.
These experiments demonstrate that the different alpha 2-adrenoceptor-mediated functions have similar stereochemical requirements in the central nervous system. Expand
Nonadrenergic imidazoline binding sites on human platelets.
  • J. Piletz, K. Sletten
  • Chemistry, Medicine
  • The Journal of pharmacology and experimental therapeutics
  • 1993
Based on differential subcellular distributions and affinity constants, human platelets appear to possess imidazoline receptors plus a novel guanabenz-sensitive site, as well as an alpha-2A adrenoceptor, which may explain certain novel platelet aggregatory properties previously ascribed to clonidine and endogenousClonidine-displacing substance(s). Expand
Use of recombinant human α2-adrenoceptors to characterize subtype selectivity of antagonist binding
Correlation analysis between results for human-type receptors and published data for their rat α 2 -adrenoceptor homologues demonstrated excellent general agreement, with some interspecies differences in the affinity of rauwolscine, phentolamine and oxymetazoline. Expand