Regulation of porcine brain alpha 2-adrenergic receptors by Na+,H+ and inhibitors of Na+/H+ exchange.

J. M. Nunnari, M. G. Repaske, S. Brandon, E. J. Cragoe, L. E. Limbird

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Previous reports from this laboratory have demonstrated that alpha 2-adrenergic receptors accelerate Na+/H+ exchange in NG108-15 neuroblastoma X glioma cells and evoke platelet secretion via a pathway involving Na+/H+ exchange. The present studies were designed to examine whether agents that interact with Na+/H+ antiporters also might influence alpha 2-adrenergic receptor-ligand interactions. We observed that Na+ decreases receptor affinity for the agonists epinephrine, norepinephrine, and UK14304 and slightly increases receptor affinity for the antagonists yohimbine and idazoxan in digitonin-solubilized preparations from porcine brain cortex. Increases in [H+] also decrease receptor affinity for agonists and cause either a slight increase or no change in receptor affinity for antagonists. Amiloride analogs accelerate the rate of [3H] yohimbine dissociation from digitonin-solubilized receptors with a relative effectiveness that parallels their ability to block Na+/H+ exchange in other systems. Interestingly, these modulatory effects of Na+,H+ and 5-amino-substituted analogs of amiloride are retained in homogeneous preparations of the alpha 2-adrenergic receptor, suggesting that the allosteric-binding sites for these agents are on the receptor-binding protein itself.

Original languageEnglish (US)
Pages (from-to)12387-12392
Number of pages6
JournalJournal of Biological Chemistry
Issue number25
StatePublished - Sep 5 1987
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry


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