Key result
Acute hyperbaric oxygen pretreatment in adult male rats resulted in inspiratory phrenic burst amplitude of +66% baseline compared to +43% with normoxia, with a larger coefficient of variation.
Why the study?
It was unknown whether phrenic motor output is altered following acute hyperbaric oxygen pretreatment.
Does acute hyperbaric oxygen pretreatment alter phrenic motor output in adult male rats?
Does acute hyperbaric oxygen pretreatment alter phrenic motor output in adult male rats?
Absolute Event Rate: 66% vs 43%
p-value: p=0.008
Acute hyperbaric oxygen pretreatment does not impact baseline phrenic output but increases the variability of phrenic long-term facilitation following acute intermittent hypoxia in rats.
HBO pretreatment may enhance AIH-induced phrenic plasticity in rats; hypothesis-generating for human respiratory control and requires clinical validation.
We studied adult male rats to determine if phrenic motor output is altered following acute hyperbaric oxygen (HBO) pretreatment. Rats were treated with 1-h of 100 % O 2 at 2 atmospheres (HBO, n = 12) or 21 % O 2 at 1 atmosphere (normoxia, n = 12) and then anesthetized and ventilated to enable phrenic nerve recordings. Baseline phrenic output and blood pressure were similar between groups. Sixty minutes after exposure to acute intermittent hypoxia (AIH), inspiratory phrenic burst amplitude was +66 ± 47 (HBO) and +43 ± 13 % baseline (normoxia). Thus, both groups expressed phrenic long-term facilitation, pLTF (time effect, P = 0.008). The pLTF magnitude had a larger coefficient of variation after HBO (71 %) vs . normoxia (30 %). This resulted from a bimodal data distribution, with 4 of 12 HBO rats showing pLTF > +70 % baseline ( vs. 0 of 12 normoxia). We conclude that acute HBO does not impact baseline phrenic output in this preparation, but further study of HBO and phrenic neuroplasticity is warranted.
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Thakre et al. (2025) studied this question. Acute hyperbaric oxygen (HBO) vs. 21% O2 at 1 atmosphere (normoxia) was evaluated on Inspiratory phrenic burst amplitude (% baseline) 60 minutes after exposure to acute intermittent hypoxia (p=0.008). Acute hyperbaric oxygen pretreatment in adult male rats resulted in inspiratory phrenic burst amplitude of +66% baseline compared to +43% with normoxia, with a larger coefficient of variation.
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