Depression by Ca2+ and Stimulation by K+ of Fictive Inspiratory Rhythm in Newborn Rat Brainstem Slices
Rhythmogenic pre-Bötzinger complex (preBötC) networks are inspiratory active in brainstem slices that are typically studied in 7–9 mM K+instead of physiological extracellular (3 mM) K+. Also superfusate Ca2+ is often high (up to 2.4 mM) compared to the most common physiological value (1.2 mM). Because both cations are potent neuromodulators, it is desirable to keep them as close as possible to normal levels for minimizing modulation of the isolated preBötC. We found that modestly raised Ca2+ depresses preBötC slice rhythm while K+ elevation counters this inhibition and low Ca2+ accelerates inspiratory bursting. A Ca2+ range of 0.75–1 mM and K+ levels between 4–6 mM may be optimal for long term stable slice rhythm.
KeywordsNonselective Cation Channel Burst Amplitude Respiratory Network Spontaneous Neuronal Activity Brainstem Slice
Supported by CIHR, AHFMR, CFI and ISRIP/ASRA. KB is a AHFMR Scientist. BP and AR have been awarded a CIHR studentship (MFN training grant).
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