Effect of alpha-adrenoceptor agonists on cell membrane potential in renal epitheloid Madin Darby canine kidney cells.
In Madin Darby canine kidney (MDCK) cells epinephrine--via alpha-adrenoceptors--leads to sustained hyperpolarization of the cell membrane. The present study defined the subtype of alpha-adrenoceptor involved. Both the alpha 1-adrenoceptor agonist, phenylephrine, and alpha 2-adrenoceptor agonists (BHT 920, guanfacine, moxonidine, oximetazoline) were able to hyperpolarize the cell membrane. The effect of epinephrine was only transient in the presence of the alpha 2-adrenoceptor antagonist, yohimbine, whereas the effect persisted in the presence of the alpha 1-adrenoceptor antagonist, prazosin. The epinephrine-induced hyperpolarization was almost abolished in the presence of both prazosin and yohimbine. In conclusion, both, alpha 1- and alpha 2-receptors are involved in the hyperpolarizing action of epinephrine.
Institute for Physiology, University of Innsbruck, Austria.
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E
Wöll
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M
Paulmichl
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F
Lang
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H
Glossmann
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects*; D004285:Dogs; D004837:Epinephrine / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D007668:Kidney / Q000166:cytology*; D008564:Membrane Potentials / Q000187:drug effects; D010646:Phentolamine / Q000494:pharmacology
D000316:Adrenergic alpha-Agonists; D007545:Isoproterenol; D004837:Epinephrine; D010646:Phentolamine