TY - JOUR
T1 - Intermittent but not sustained moderate hypoxia elicits long-term facilitation of hypoglossal motor output
AU - Wilkerson, Julia E.R.
AU - Devinney, Michael
AU - Mitchell, Gordon S.
N1 - Publisher Copyright:
© 2017
PY - 2018/10
Y1 - 2018/10
N2 - Phrenic long-term facilitation (pLTF) is a form of serotonin-dependent respiratory motor plasticity induced by moderate acute intermittent hypoxia (AIH), but not by moderate acute sustained hypoxia (ASH) of similar cumulative duration. Thus, moderate AIH-induced pLTF is sensitive to the pattern of hypoxia. On the other hand, pLTF induced by severe AIH protocols is neither pattern sensitive nor serotonin dependent (it converts to an adenosine-dependent mechanism). Although moderate AIH also induces hypoglossal LTF (hLTF), no data are available concerning its sensitivity/insensitivity to the pattern of hypoxia. Since hLTF following moderate hypoxia is serotonin-dependent, we hypothesized that hLTF is pattern-sensitive, similar to serotonin-dependent pLTF. Integrated hypoglossal nerve activity was recorded in urethane-anesthetized, vagotomized, paralyzed, and ventilated rats exposed to isocapnic AIH (3, 5 min episodes of 11% O2) or ASH (a single 25 min episode of 11% O2). Similar to previous studies of pLTF, hypoglossal motor output was elevated for more than 1 h following AIH (50 ± 20%, p < 0.01), but not ASH (–6 ± 9%, p > 0.05). Frequency LTF was not observed following either hypoxic exposure. Thus, in agreement with our hypothesis, hypoglossal LTF following moderate AIH is pattern-sensitive, similar to phrenic LTF.
AB - Phrenic long-term facilitation (pLTF) is a form of serotonin-dependent respiratory motor plasticity induced by moderate acute intermittent hypoxia (AIH), but not by moderate acute sustained hypoxia (ASH) of similar cumulative duration. Thus, moderate AIH-induced pLTF is sensitive to the pattern of hypoxia. On the other hand, pLTF induced by severe AIH protocols is neither pattern sensitive nor serotonin dependent (it converts to an adenosine-dependent mechanism). Although moderate AIH also induces hypoglossal LTF (hLTF), no data are available concerning its sensitivity/insensitivity to the pattern of hypoxia. Since hLTF following moderate hypoxia is serotonin-dependent, we hypothesized that hLTF is pattern-sensitive, similar to serotonin-dependent pLTF. Integrated hypoglossal nerve activity was recorded in urethane-anesthetized, vagotomized, paralyzed, and ventilated rats exposed to isocapnic AIH (3, 5 min episodes of 11% O2) or ASH (a single 25 min episode of 11% O2). Similar to previous studies of pLTF, hypoglossal motor output was elevated for more than 1 h following AIH (50 ± 20%, p < 0.01), but not ASH (–6 ± 9%, p > 0.05). Frequency LTF was not observed following either hypoxic exposure. Thus, in agreement with our hypothesis, hypoglossal LTF following moderate AIH is pattern-sensitive, similar to phrenic LTF.
KW - Control of breathing
KW - Hypoxia
KW - Pattern
KW - Plasticity
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U2 - 10.1016/j.resp.2017.10.005
DO - 10.1016/j.resp.2017.10.005
M3 - Article
C2 - 29074449
AN - SCOPUS:85032813928
SN - 1569-9048
VL - 256
SP - 15
EP - 20
JO - Respiratory Physiology and Neurobiology
JF - Respiratory Physiology and Neurobiology
ER -