Effect of arterial [H+] on threshold PCO2 of the respiratory system in vagotomized and carotid sinus nerve denervated cats.

Kuwana, Shun-ichi; Natsui, Teijiro

doi:10.1113/jphysiol.1981.sp013860

Cited by 9 publications

(1 citation statement)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Unilateral cold block of CSN. The Pth,co2 levels under normoxia were similar to those obtained before and after denervation of CSN, as described in the preceding paper (KUWANA and NATSUI, 1981): 24.7+0.8 Torr in CSN-intact and 25.8±0.8 Torr in CSN-denervated cats. The Pth ,co2 level of the CSN unilateral intact cats (before cold block) in the present study did not differ from that in the bilateral intact ones.…”

Section: Discussionsupporting

confidence: 86%

Effect of inactivation of carotid sinus nerve by cold block on phrenic nerve activity in cats.

Kuwana

Natsui

1985

Jpn.J.Physiol

View full text Add to dashboard Cite

The effect of the elimination of input via the carotid chemoreceptor on respiratory output was examined quantitatively in anesthetized, vagotomized, and paralyzed cats. The integrated phrenic nerve activity (PNA) was recorded as an indication of output of the respiratory center. Also, the elimination of the carotid chemoreflex drive was repeatedly done by a cold block of the carotid sinus nerve at various Pco2 levels during hyperoxia, normoxia, and hypoxia. The blockade induced a reduction in PNA at each Pco2 level in every Pot group. If the highest PNA value recorded at a high Pco2 in each Pot condition was assigned a value of 100%, the reduction of the PNA by the blockade, i.e., the respiratory effect of the carotid chemoreflex drive, would be slightly larger during normoxia (16%) than during hyperoxia (8.7 %), but would be independent of Pco2. During hypoxia, this chemoreflex effect was about 40% of a low P02, and decreased with increments of P02, finally reaching about 20 of a high Pco2 level. Furthermore, the relative contribution of the carotid chemoreceptor to respiratory output, expressed as the ratio of the PNA reduction during blockade to the PNA before blockade, was inversely proportional to both Pot and Pco2. It is concluded that the interaction of the peripheral and central chemoreceptor drive is hypoadditive at moderate and high Pco2 levels in anesthetized cats, and this interatction is emphasized by central hypoxia. According to a electrophysiological study, it has been confirmed that the carotid chemoreceptor's discharges increased with the increasing of Pco2 ([H+]) or the decreasing of Pot, and the two stimuli interacted multiplicatively at the site of chemoreceptors (EYZAGUIRRE and LEWIN, 1961;LAHIRI and DELANEY, 1975a;EYZAGUIRRE et al., 1983). However, there is disagreement as to what kind of interaction between the inputs from the peripheral and central chemoreceptors occurs in various species. In conscious man the interaction was found to be

show abstract

Section: Discussionsupporting

confidence: 86%

Effect of inactivation of carotid sinus nerve by cold block on phrenic nerve activity in cats.

Kuwana

Natsui

1985

Jpn.J.Physiol

View full text Add to dashboard Cite

show abstract

Metabolic Acid-Base Status and the Role of Carotid Chemoreceptors in Hyperoxic Breathing

Kiwull-Schöne

Bungart²,

Kiwull³

1994

Advances in Experimental Medicine and Biology

View full text Add to dashboard Cite

Anoxic disturbance of the isolated respiratory network of neonatal rats

1995

View full text Add to dashboard Cite

Tissue oxygen (PO2), K+ (aKe), pH (pHe) and Ca2+ ([Ca2+]e) were measured in the region of the ventral respiratory group (VRG) in the in vitro brainstem-spinal cord preparation of neonatal rats. During tissue anoxia, elicited by superfusion of N2-gassed solutions, an initial increase in the frequency of respiratory activity, lasting between 2 and 12 min, turned into a frequency depression. During anoxia periods of up to 60 min, respiratory activity persisted in solutions containing CO2/bicarbonate, whereas a complete blockade was observed after 15-25 min in N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid- (Hepes)-buffered salines. After such anoxic apnea, respiratory rhythmicity could be reactivated by superfusion of hypoxic, CO2/bicarbonate-buffered solutions. In both types of hypoxic solutions, aKe increased by maximally 1.5 mM, whereas an initial increase of pHe by up to 0.05 pH units turned, after 2-4 min, into an acidification which could exceed 0.5 pH units. In contrast, [Ca2+]e remained unaffected by anoxia. Addition of 2-5 mM cyanide (CN-) to oxygenated Hepes-buffered saline evoked an increase in PO2 in the VRG from 100 to more than 300 mmHg. The effects of CN- on respiratory activity, aKe and pHe were almost identical to those during anoxia. In oxygenated, CO2/bicarbonate-free solutions of different pH, however, an increase in pHe in the VRG led to a decrease in respiratory frequency, whereas a fall of pHe produced a frequency acceleration. A rise of aKe in the VRG by more than 2 mM as induced by superfusion of a 7 mM K+ solution led to a sustained increase of respiratory frequency. The results indicate that blockade of aerobic metabolism does not severely perturb K+ and Ca2+ homeostasis and that the biphasic response to anoxia is not directly related to the observed changes in PO2, aKe, pHe, or [Ca2+]e. In the respiratory network of neonatal mammals, CO2 might provide a stimulus for long-term maintenance of respiratory activity under oxygen depletion.

show abstract

Effect of arterial [H+] on threshold PCO2 of the respiratory system in vagotomized and carotid sinus nerve denervated cats.

Cited by 9 publications

References 29 publications

Effect of inactivation of carotid sinus nerve by cold block on phrenic nerve activity in cats.

Effect of inactivation of carotid sinus nerve by cold block on phrenic nerve activity in cats.

Metabolic Acid-Base Status and the Role of Carotid Chemoreceptors in Hyperoxic Breathing

Anoxic disturbance of the isolated respiratory network of neonatal rats

Contact Info

Product

Resources

About