Subclassification of alpha-adrenergic receptors by direct binding studies

Wood, Catherine L.; Arnett, Carroll D.; Clarke, William R.; Tsai, Bie Shung; Lefkowitz, Robert J.

doi:10.1016/0006-2952(79)90424-6

Cited by 135 publications

(21 citation statements)

References 28 publications

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“…Thus it is of interest that for human platelets the clonidine analogue, UK-14,304, behaves as a full agonist exhibiting a2-selectivity and showing, in contrast to clonidine, no greater variability in the extent or concentration-dependence of the response in different donors than is observed for adrenaline. The relative inefficiency of clonidine as an agonist at the platelet a2-adrenoceptor does not result from defective binding to the receptor since this selective a-agonist exhibits a higher affinity than adrenaline for both human and rabbit platelet a-adrenoceptors (Wood et at., 1979). However, for human platelets yohimbine is significantly less effective as an antagonist of the response to clonidine than of that to adrenaline or UK-14,304.…”

Section: Discussionmentioning

confidence: 99%

Interaction of Selective Α‐adrenoceptor Agonists and Antagonists With Human and Rabbit Blood Platelets

Grant

Scrutton

1980

British J Pharmacology

109

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The selectivity of α‐adrenoceptors mediating the pro‐aggregatory response of human and rabbit platelets to adrenaline and the conditions required to permit expression of an aggregatory response to partial agonists at these α‐adrenoceptors have been studied. Yohimbine causes effective blockade of the pro‐aggregatory responses whereas indoramin and prazosin are ineffective. The clonidine analogue, UK‐14304, is nearly as effective as adrenaline in inducing an aggregatory response in human platelets and a pro‐aggregatory response in rabbit platelets. Cross‐tachyphylaxis between adrenaline and UK‐14304 has been demonstrated. Clonidine is a weak agonist for the pro‐aggregatory response of rabbit platelets and in some donors for the aggregatory response of human platelets. Methoxamine induces a pro‐aggregatory response in human platelets which is blocked by indoramin or prazosin but not by yohimbine. No such response to methoxamine is observed in rabbit platelets. The divalent cation ionophore, A‐23187, induces an aggregatory response to clonidine (in platelets from a non‐responsive donor), phenylephrine and methoxamine in human platelets and to adrenaline, UK‐14304 and clonidine in rabbit platelets. A secretory response to clonidine is also induced by A‐23187 in human platelets. The adenylate cyclase inhibitor, SQ‐22536, is ineffective in either inducing a response to the α‐agonists or potentiating the effect of A‐23187. The aggregatory responses to adrenaline and UK‐14304 in rabbit platelets and to clonidine in human and rabbit platelets, which can be induced by A‐23187, are blocked by yohimbine but not by prazosin or indoramin. From these studies we conclude that the pro‐aggregatory responses of human and rabbit platelets to adrenaline are mediated primarily by α2‐adrenoceptors. The presence of α1‐adrenoceptors on human platelets is confirmed but these receptors do not appear to be present on rabbit platelets. The conditions required for expression of an aggregatory response to partial agonists at the human and rabbit platelet α‐adrenoceptors implicate an increase in cytosolic Ca2+ concentration as a key event in stimulus‐response coupling but do not indicate such a role for depression of cyclic adenosine‐3′,5′‐monophosphate concentration.

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Section: Discussionmentioning

confidence: 99%

Interaction of Selective Α‐adrenoceptor Agonists and Antagonists With Human and Rabbit Blood Platelets

Grant

Scrutton

1980

British J Pharmacology

109

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“…The stimulation of a2-adrenoceptors increased plasma glucose levels (Nakadate et al, 1980) and inhibited immunoreactive insulin (IRI) release from pancreatic islets (Smith & Porte, 1976;Nakadate et al, 1980). However, since DHE has a high affinity for both ocand a2-adrenoceptors (Wood et al, 1979), previous studies have failed to define adequately the ca-adrenoceptor subtypes involved in lithium action. Selective a-adrenoceptor antagonists have different effects on the changes in plasma glucose and insulin levels induced by stimulation of a-adrenoceptors (Yamazaki et al, 1982).…”

Section: Introductionmentioning

confidence: 99%

Role of adrenoceptors in vitro and in vivo in the effects of lithium on blood glucose levels and insulin secretion in the rat

Fontela

Hermida

Gómez-Acebo

1990

British J Pharmacology

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1 Pretreatment of rats with the non-selective a-adrenoceptor antagonist dihydroergotamine counteracts the inhibition of glucose-induced insulin secretion caused by lithium both in vitro and in vivo. The present study was therefore carried out to specify further which type of adrenoceptor is involved in lithiuminduced hyperglycaemia and inhibition of insulin secretion. 2 The lithium-induced effects were reversibly blocked by pretreatment of rats with the a2-adrenoceptor antagonist yohimbine or a combination of yohimbine and the non-selectivefl-receptor antagonist propranolol, whereas the a,-receptor antagonist prazosin and propranolol alone were ineffective in blocking these effects. 3 These findings suggest that the effects of lithium on plasma glucose and insulin levels are mediated mainly by the stimulation of a2-adrenoceptors.

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“…Data obtained through the use of subtype-selective antagonists suggest that these receptors are predominantly of the ^-subtype mediating vascular smooth muscle contraction. 17 …”

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confidence: 99%

Characterization of postsynaptic alpha-adrenergic receptors by [3H]-dihydroergocryptine binding in muscular arteries from the rat mesentery.

Colucci¹,

Gimbrone²,

Alexander³

1980

Hypertension

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Subclassification of alpha-adrenergic receptors by direct binding studies

Cited by 135 publications

References 28 publications

Interaction of Selective Α‐adrenoceptor Agonists and Antagonists With Human and Rabbit Blood Platelets

Interaction of Selective Α‐adrenoceptor Agonists and Antagonists With Human and Rabbit Blood Platelets

Role of adrenoceptors in vitro and in vivo in the effects of lithium on blood glucose levels and insulin secretion in the rat

Characterization of postsynaptic alpha-adrenergic receptors by [3H]-dihydroergocryptine binding in muscular arteries from the rat mesentery.

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