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Quinine blocks the high conductance, calcium‐activated potassium channel in rat pancreatic β‐cells
Author(s) -
Mancilla Edna,
Rojas Eduarde
Publication year - 1990
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(90)80078-w
Subject(s) - potassium channel , blockade , quinine , chemistry , biophysics , endocrinology , medicine , membrane potential , calcium activated potassium channel , conductance , biology , biochemistry , immunology , physics , receptor , malaria , condensed matter physics
The [Ca 2+ ] i ‐activated K + ‐channel, one of the 3 K + ‐channels described in pancreatic β‐cells, is a high conductance, voltage‐dependent K + ‐channel. Quinine, known to block [Ca 2+ ] i ‐activated K + ‐channels in other cells, has been described to block the silent phase between the bursts of glucose‐evoked electrical activity in mouse pancreatic β‐cells, and to inhibit K + efflux from rat pancreatic islets. We report here that quinine blocks the [Ca 2+ i ‐activated K + ‐channel in rat pancreatic β‐cells, from the external side of the membrane. We also show that the blockade is characterized by fast flickering of the K + ‐channel between the open and closed state. Mean open and closed times within bursts were found to be exponentially distributed, suggesting that the blockade by quinine involves obstruction on the K + flow through the open to be exponentially distributed, suggesting that the blockade by quinine involves obstruction on the K + flow through the open channel.