Potassium channels opened by noradrenaline and other transmitters in excised membrane patches of guinea-pig submucosal neurones

Ke-Zhong Shen, R. A. North, A. Surprenant

Research output: Contribution to journalArticle

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Abstract

1. Unitary potassium currents were recorded in outside-out patches of membrane from guinea-pig submucosal neurones. The actions of α2-adrenoceptor agonists, somatostatin and [Met5]enkephalin were studied. 2. Three main groups of background potassium channels were active. At -70 mV with 160 mM-potassium on both sides of the membrane, they had conductances of 30-65 (small), 120-160 (intermediate) and 220-260 pS (large). 3. The open channel current-voltage relation showed only constant-field rectification. Extracellular barium (2 mM) and caesium (2 mM) decreased inward but not outward currents. Tetraethylammonium (10 mM) had no effect. 4. Noradrenaline, somatostatin and [Met5]enkephalin each increased the open probability of all three classes of channel when two or more unitary amplitude channels were active in the membrane patch. Agonists were ineffective when no channel, or a single channel, was discernible in the patch. Agonists did not cause the appearance of unitary currents distinct from those seen prior to their application. 5. The effect of the agonists required intracellular guanosine 5'-triphosphate. 6. The results show that the hyperpolarization of submucosal plexus neurones by noradrenaline, somatostatin and [Met5]enkephalin results from the increased opening of at least three types of background potassium channel, and that the coupling from the receptors to the channels is maintained in excised membrane patches.

Original languageEnglish (US)
Pages (from-to)581-599
Number of pages19
JournalJournal of Physiology
Volume445
StatePublished - 1992

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Potassium Channels
Tandem Pore Domain Potassium Channels
Enkephalins
Norepinephrine
Guinea Pigs
Somatostatin
Neurons
Membranes
Potassium
Submucous Plexus
Cesium
Tetraethylammonium
Barium
Guanosine Triphosphate
Adrenergic Receptors

ASJC Scopus subject areas

  • Physiology

Cite this

Potassium channels opened by noradrenaline and other transmitters in excised membrane patches of guinea-pig submucosal neurones. / Shen, Ke-Zhong; North, R. A.; Surprenant, A.

In: Journal of Physiology, Vol. 445, 1992, p. 581-599.

Research output: Contribution to journalArticle

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N2 - 1. Unitary potassium currents were recorded in outside-out patches of membrane from guinea-pig submucosal neurones. The actions of α2-adrenoceptor agonists, somatostatin and [Met5]enkephalin were studied. 2. Three main groups of background potassium channels were active. At -70 mV with 160 mM-potassium on both sides of the membrane, they had conductances of 30-65 (small), 120-160 (intermediate) and 220-260 pS (large). 3. The open channel current-voltage relation showed only constant-field rectification. Extracellular barium (2 mM) and caesium (2 mM) decreased inward but not outward currents. Tetraethylammonium (10 mM) had no effect. 4. Noradrenaline, somatostatin and [Met5]enkephalin each increased the open probability of all three classes of channel when two or more unitary amplitude channels were active in the membrane patch. Agonists were ineffective when no channel, or a single channel, was discernible in the patch. Agonists did not cause the appearance of unitary currents distinct from those seen prior to their application. 5. The effect of the agonists required intracellular guanosine 5'-triphosphate. 6. The results show that the hyperpolarization of submucosal plexus neurones by noradrenaline, somatostatin and [Met5]enkephalin results from the increased opening of at least three types of background potassium channel, and that the coupling from the receptors to the channels is maintained in excised membrane patches.

AB - 1. Unitary potassium currents were recorded in outside-out patches of membrane from guinea-pig submucosal neurones. The actions of α2-adrenoceptor agonists, somatostatin and [Met5]enkephalin were studied. 2. Three main groups of background potassium channels were active. At -70 mV with 160 mM-potassium on both sides of the membrane, they had conductances of 30-65 (small), 120-160 (intermediate) and 220-260 pS (large). 3. The open channel current-voltage relation showed only constant-field rectification. Extracellular barium (2 mM) and caesium (2 mM) decreased inward but not outward currents. Tetraethylammonium (10 mM) had no effect. 4. Noradrenaline, somatostatin and [Met5]enkephalin each increased the open probability of all three classes of channel when two or more unitary amplitude channels were active in the membrane patch. Agonists were ineffective when no channel, or a single channel, was discernible in the patch. Agonists did not cause the appearance of unitary currents distinct from those seen prior to their application. 5. The effect of the agonists required intracellular guanosine 5'-triphosphate. 6. The results show that the hyperpolarization of submucosal plexus neurones by noradrenaline, somatostatin and [Met5]enkephalin results from the increased opening of at least three types of background potassium channel, and that the coupling from the receptors to the channels is maintained in excised membrane patches.

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