The Effect of Polycythemia on Respiratory Sensitivity

Perception of effort and respiratory sensitivity during exposure to ozone

Ergonomics ◽

10.1080/00140138108924858 ◽

1981 ◽

Vol 24 (5) ◽

pp. 365-374 ◽

Cited By ~ 8

Author(s):

PATRICIA M. MIHEVIC ◽

JEFFREY A. GLINER ◽

STEVEN M. HORVATH

Keyword(s):

Perception Of Effort ◽

Respiratory Sensitivity

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Maturation of steady-state CO2 sensitivity in vagotomized anesthetized lambs

Journal of Applied Physiology ◽

10.1152/jappl.1992.72.4.1255 ◽

1992 ◽

Vol 72 (4) ◽

pp. 1255-1260 ◽

Cited By ~ 4

Author(s):

A. H. Jansen ◽

S. Ioffe ◽

V. Chernick

Keyword(s):

Steady State ◽

Test Procedure ◽

Nerve Section ◽

Co2 Response ◽

Arterial Pco2 ◽

Co2 Sensitivity ◽

Carotid Bodies ◽

Before And After ◽

End Tidal ◽

Respiratory Sensitivity

The maturation of the respiratory sensitivity to CO2 was studied in three groups of anesthetized (ketamine, acepromazine) lambs 2–3, 14–16, and 21–22 days old. The lambs were tracheostomized, vagotomized, paralyzed, and ventilated with 100% O2. Phrenic nerve activity served as the measure of respiration. The lambs were hyperventilated to apneic threshold, and end-tidal PCO2 was raised in 0.5% steps for 5–7 min each to a maximum 7–8% and then decreased in similar steps to apneic threshold. The sinus nerves were cut, and the CO2 test procedure was repeated. Phrenic activity during the last 2 min of every step change was analyzed. The CO2 sensitivity before and after sinus nerve section was determined as change in percent minute phrenic output per Torr change in arterial PCO2 from apneic threshold. Mean apneic thresholds (arterial PCO2) were not significantly different among the groups: 34.8 +/- 2.08, 32.7 +/- 2.08, and 34.7 +/- 2.25 (SE) Torr for 2- to 3-, 14- to 16-, and 21- to 22-day-old lambs, respectively. After sinus denervation, apneic thresholds were raised in all groups [39.9 +/- 2.08, 40.9 +/- 2.08, and 45.3 +/- 2.25 (SE) Torr, respectively] but were not different from each other. CO2 response slopes did not change with age before or after sinus nerve section. We conclude that carotid bodies contribute to the CO2 response during hyperoxia by affecting the apneic threshold but do not affect the steady-state CO2 sensitivity and the central chemoreceptors are functionally mature shortly after birth.

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