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. Author manuscript; available in PMC: 2020 Aug 1.
Published in final edited form as: Respir Physiol Neurobiol. 2019 May 3;266:54–65. doi: 10.1016/j.resp.2019.04.014

Table 1.

Frequency plasticity in rodent preparations.

Age, Species, Preparation Stimulus Frequency plasticity Reference
1–2 month old awake, intact rats 12 5-min bouts of 12% oxygen (5-min normoxic intervals) 12–16% increase in breath frequency at 45 min post-stimulus McGuire and Ling (2005)
1-month old awake, intact rats 5 5-min bouts of 12% oxygen (5-min normoxic intervals) < 10% increase in breath frequency at 45 min post-stimulus
urethane anesthetized P14–15 rats 40% O2/4% CO2 under urethane anesthesia to obtain baseline breathing data 20–40% increase in breathing frequency above of baseline after 60 min Reid and Solomon (2014)
3 5-min bouts of 8% O2/4% CO2 with 5-min intervals of 40% O2/4% CO2
semi-intact in situ working-heart brainstem preparations from P15–P25 rats Baseline conditions, solution equilibrated with 95% O2/5% CO2, Intermittent severe, moderate, and mild hypoxia increase respiratory frequency above baseline by 40%, 40% and 25%, respectively, 60-min after the exposure Tadjalli et al. (2007)
3 5-min bouts of hypoxic solution with 5-min intervals at different hypoxic levels:
Severe – 10% O2/5% CO2/85% N2
Moderate – 20% O2/5% CO2/75% N2
Mild – 40% O2/5% CO2/55% N2
intact newborn P1, P4, P10 rats 10 60-s bouts of 5% O2 with 2-min of reoxygenation, separated by 5-min normoxic intervals No frequency plasticity. Long-lasting (> 120 min) increases in ventilation and tidal volume are observed only in P10 rats Julien et al. (2008)
brainstem-spinal cord preparations from P2 mice 3 3-min bouts of bath-applied hypoxic solution (95% N2/5% CO2; PO2 = ~15kPa) with 5-min intervals of 95% O2/5% CO2) 34% increase in motor burst frequency after 40 min of washout with normoxic solution (95% O2/5% CO2) Berner et al. (2007)
rhythmically-active medullary slices from P0–P7 mice intermittent bath application of hypoxic solution (95% N2/5% CO2) 40-65% increase in motor burst frequency when 3 3-min hypoxic solution exposures are separated by 5-min intervals compared to only a 10–30% increase with 10-min intervals Blitz and Ramirez (2002)