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κ‐Opioid receptor‐mediated enhancement of the hyperpolarization‐activated current ( I h ) through mobilization of intracellular calcium in rat nucleus raphe magnus
Author(s) -
Pan Zhizhong Z.
Publication year - 2003
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j..2003.t01-1-00765.x
Subject(s) - nucleus raphe magnus , hyperpolarization (physics) , nucleus , chemistry , raphe , neuroscience , raphe nuclei , calcium in biology , receptor , biophysics , biology , serotonergic , serotonin , biochemistry , stereochemistry , nuclear magnetic resonance spectroscopy
The hyperpolarization‐activated current ( I h ) is important in the control of resting membrane potential, in the regulation of network firing pattern and in the modulation of presynaptic transmitter release in central neurons. Recent studies on native and cloned I h channels have demonstrated that the I h channel is commonly modulated by cAMP through a positive shift in its voltage dependence without a change in its maximum current. The present study demonstrates that activation of κ‐opioid receptors enhances I h by increasing its maximum current in brainstem neurons in the nucleus raphe magnus. Agents that interfere with the release of intracellular calcium from calcium stores altered the maximum I h and significantly attenuated the κ‐receptor‐mediated enhancement of I h . These results suggest that κ‐opioid receptors enhance the maximum I h by mobilizing intracellular calcium from calcium stores. This provides a physiological function for κ‐receptor‐stimulated calcium release and may suggest another I h ‐regulating mechanism by intracellular calcium in central neurons.