Fig 1.
Respiratory motor activity under normocapnic conditions and hypercapnic acidosis.
(A) Original and integrated traces of CN, SLN, RLN, and PN activity during normocapnia (5% CO2, 95% O2), hypercapnia (8% CO2, 92% O2), and recovery (5% CO2, 95% O2). (B) Traces averaged from consecutive integrated sweeps for 1 min in the preparation shown in (A). The black and gray traces show the averaged traces during hypercapnia and normocapnia, respectively. The filled arrowheads show the onset of the nerve discharges. The open arrowheads show the pre-inspiration (pre-I) discharges. ‘I’ and ‘E’ demonstrate the inspiratory and expiratory phases, respectively. (C) Original and integrated traces of the CN, SLN, HGN, and PN activity obtained from a different preparation from (A). (D) Traces averaged from consecutive integrated sweeps for 1 min in the preparation shown in (C).
Table 1.
The onset of the CN, SLN, HGN and RLN discharges in relation to that of the PN discharge during normocapnia (5% CO2) and hypercapnia (8% CO2).
Fig 2.
The discharge patterns of the CN, SLN, RLN, and HGN under normocapnic conditions.
Averaged traces from two preparations shown in Fig 1 were normalized via the peak amplitude.
Table 2.
Comparison of variables of PN activity during normocapnia (5% CO2) and hypercapnia (8% CO2) (n = 21).
Fig 3.
The discharge patterns of the CN, SLN, RLN, and HGN in hypercapnic acidosis.
The averaged traces from two preparations shown in Fig 1 were normalized via the peak amplitude of the pre-I discharges.
Fig 4.
Comparison between intercostal nerve (ICN) activity and CN activity.
(A) Original and integrated traces of the ICN, CN, and PN activity during normocapnia (5% CO2, 95% O2), hypercapnia (8% CO2, 92% O2), and recovery (5% CO2, 95% O2). (B) Traces averaged from consecutive integrated sweeps for 1 min in the preparation shown in (A). ‘Pre-I d’ shows the duration of pre-I discharge in the ICN and CN. The filled arrowheads show the onset of the nerve discharges. (C) Correlation between the duration of the CN discharge in the pre-I phase and duration of the ICN discharge in the pre-I phase in the preparation shown in (A).
Fig 5.
Correlation between abdominal nerve (AbN) activity and CN activity.
(A) Original and integrated traces of AbN, CN, and PN activity during normocapnia (5% CO2, 95% O2), hypercapnia (8% CO2, 92% O2), and recovery (5% CO2, 95% O2). (B) Traces averaged from consecutive integrated sweeps for 1 min in the preparation shown in (A). The filled arrowheads show the onset of nerve discharges. (C) Comparison of the duration of the AbN pre-I discharge, CN pre-I discharge, and respiratory cycle in the preparation shown in (A). Black bars show the times that the traces in (A) were recorded. The black arrow shows the time point at which the respiratory duration became shortest. The white arrow shows the time point at which the abdominal discharge appeared. (D) Correlation between the duration of the CN pre-I phase discharge and duration of the AbN pre-I discharge in the preparation shown in (A).