Ventilatory response to hyperoxia in newborn mice heterozygous for the transcription factor Phox2b

2006 ◽  
Vol 290 (6) ◽  
pp. R1691-R1696 ◽  
Author(s):  
N. Ramanantsoa ◽  
V. Vaubourg ◽  
S. Dauger ◽  
B. Matrot ◽  
G. Vardon ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Ventilatory Response ◽  
Minute Ventilation ◽  
Whole Body ◽  
Wild Type ◽  
Peripheral Chemoreceptor ◽  
Newborn Mice ◽  
Apnea Duration ◽  
Autonomic Reflex ◽  
Hypoventilation Syndrome

Heterozygous mutations of the transcription factor PHOX2B have been found in most patients with central congenital hypoventilation syndrome, a rare disease characterized by sleep-related hypoventilation and impaired chemosensitivity to sustained hypercapnia and sustained hypoxia. PHOX2B is a master regulator of autonomic reflex pathways, including peripheral chemosensitive pathways. In the present study, we used hyperoxic tests to assess the strength of the peripheral chemoreceptor tonic drive in Phox2b+/− newborn mice. We exposed 69 wild-type and 67 mutant mice to two hyperoxic tests (12-min air followed by 3-min 100% O2) 2 days after birth. Breathing variables were measured noninvasively using whole body flow plethysmography. The initial minute ventilation decrease was larger in mutant pups than in wild-type pups: −37% (SD 13) and −25% (SD 18), respectively, P < 0.0001. Furthermore, minute ventilation remained depressed throughout O2 exposure in mutants, possibly because of their previously reported impaired CO2 chemosensitivity, whereas it returned rapidly to the normoxic level in wild-type pups. Hyperoxia considerably increased total apnea duration in mutant compared with wild-type pups ( P = 0.0001). A complementary experiment established that body temperature was not influenced by hyperoxia in either genotype group and, therefore, did not account for genotype-related differences in the hyperoxic ventilatory response. Thus partial loss of Phox2b function by heterozygosity did not diminish the tonic drive from peripheral chemoreceptors.

Effects of temperature on ventilatory response to hypercapnia in newborn mice heterozygous for transcription factor Phox2b

2007 ◽  
Vol 293 (5) ◽  
pp. R2027-R2035 ◽  
Author(s):  
N. Ramanantsoa ◽  
V. Vaubourg ◽  
B. Matrot ◽  
G. Vardon ◽  
S. Dauger ◽  
...  
Keyword(s):  
Heart Rate ◽  
Transcription Factor ◽  
Temperature Regulation ◽  
Ventilatory Response ◽  
Whole Body ◽  
Wild Type ◽  
Newborn Mice ◽  
Phox2b Gene ◽  
Ambient Temperatures ◽  
Hypercapnic Ventilatory Response

Congenital central hypoventilation syndrome (CCHS) is a rare disease with variable severity, generally present from birth and chiefly characterized by impaired chemosensitivity to hypercapnia. The main cause of CCHS is a mutation in the PHOX2B gene, which encodes a transcription factor involved in the development of autonomic medullary reflex pathways. Temperature regulation is abnormal in many patients with CCHS. Here, we examined whether ambient temperature influenced CO2 sensitivity in a mouse model of CCHS. A weak response to CO2 at thermoneutrality (32°C) was noted previously in 2-day-old mice with an invalidated Phox2b allele ( Phox2b+/−), compared with wild-type littermates. We exposed Phox2b+/− pups to 8% CO2 at three ambient temperatures (TAs): 29°C, 32°C, and 35°C. We measured breathing variables and heart rate (HR) noninvasively using a novel whole body flow plethysmograph equipped with contact electrodes. Body temperature and baseline breathing increased similarly with TA in mutant and wild-type pups. The hypercapnic ventilatory response increased linearly with TA in both groups, while remaining smaller in mutant than in wild-type pups at all TAs. The differences between the absolute increases in ventilation in mutant and wild-type pups become more pronounced as temperature increased above 29°C. The ventilatory abnormalities in mutant pups were not associated with significant impairments of heart rate control. In both mutant and wild-type pups, baseline HR increased with TA. In conclusion, TA strongly influenced the hypercapnic ventilatory response in Phox2b+/− mutant mice. These findings suggest that abnormal temperature regulation may contribute to the severity of respiratory impairments in CCHS patients.

Endogenous brain erythropoietin is a potent sex-specific respiratory stimulant in adult and newborn mice

2015 ◽  
Vol 118 (11) ◽  
pp. 1386-1395 ◽  
Author(s):  
Orlane Ballot ◽  
Vincent Joseph ◽  
Jorge Soliz
Keyword(s):  
Ventilatory Response ◽  
Minute Ventilation ◽  
Whole Body ◽  
Newborn Mice ◽  
Male And Female ◽  
Female Mice ◽  
Specific Effects ◽  
Respiratory Stimulant ◽  
Males And Females ◽  
Whole Body Plethysmography

We tested the hypothesis that endogenous brain Epo is a respiratory stimulant. Adult (3 mo) and newborn (10 days) male and female mice received an intracisternal (cisterna magna) injection of soluble Epo receptor (sEpoR; competes with EpoR to bind Epo; 50 μg/ml) or vehicle (0.1% BSA in PBS). Twenty-four hours after injection, we used whole body plethysmography to record minute ventilation (V̇e) tidal volume (VT), respiratory frequency ( fR), O2 consumption (V̇o2), and CO2 production (V̇co2) under normoxia and progressive exposure to hypoxia (12-10-6% O2; 10 min each). In adult male and female mice sEpoR decreased normoxic V̇e (−25%), due to a decrease of VT in males and fR in females. Moreover, sEpoR injection decreased the ventilatory response to 12% O2, assessed as V̇e/V̇o2 or V̇e/V̇co2, in male but not in female mice. In newborn male and female mice sEpoR decreased V̇e (−37% in males, −59% in females) and VT (−38% in males, −47% in females) in normoxia and fR in females. During hypoxia, sEpoR decreased V̇e/V̇o2 and V̇e/V̇co2 in mice of both sexes. Upon extreme hypoxia (6% O2), the newborn mice treated with sEpoR showed respiratory depression, signs of asphyxia (gasping) and a high mortality rate in males and females. We concluded that endogenous brain Epo is a potent respiratory stimulant under normoxia and hypoxia in adult and newborn mice. Because sex-specific effects are different in newborn male and female, sex steroids secreted at different ages mice appear to modulate the effects of Epo on respiratory regulation in normoxia and in response to hypoxia.

Peripheral chemoreceptor function in children with the congenital central hypoventilation syndrome

1993 ◽  
Vol 74 (1) ◽  
pp. 379-387 ◽  
Author(s):  
D. Gozal ◽  
C. L. Marcus ◽  
D. Shoseyov ◽  
T. G. Keens
Keyword(s):  
Vital Capacity ◽  
Minute Ventilation ◽  
Acute Hypoxia ◽  
Clinical Manifestations ◽  
Congenital Central Hypoventilation Syndrome ◽  
Tidal Breathing ◽  
Peripheral Chemoreceptor ◽  
Ventilatory Responses ◽  
Central Hypoventilation ◽  
Hypoventilation Syndrome

In children with the congenital central hypoventilation syndrome (CCHS), some patients require mechanical ventilation during sleep, whereas others need respiratory assistance even when awake. The cause of this disparity is unclear. We hypothesized that differences in peripheral chemoreceptor response (PCR) could provide an explanatory mechanism for this disparity in clinical manifestations. PCR was measured in five children with CCHS and five sex- and age-matched controls by measuring the ventilatory responses induced by 100% O2 breathing, five tidal breaths of 100% N2, and vital capacity breaths of 5% and 15% CO2 in O2 and 5% CO2–95% N2. Tidal breathing of 100% O2 resulted in similar ventilatory responses in CCHS patients and controls with various changes dependent on the method of analysis of response used. Acute hypoxia by N2 tidal breathing resulted in a 39.2 +/- 22% increase in respiratory rate in CCHS patients and a 15.1 +/- 11.1% increase in controls (P < 0.05), with similar increases in minute ventilation (VE) of 124 +/- 69% and 85 +/- 11%, respectively. Vital capacity breaths of each of the CO2-containing gas mixtures induced similar increases in VE in CCHS patients and controls. The changes in VE obtained with 15% CO2–85% O2 and with 5% CO2–95% N2 were significantly greater than those with 5% CO2–95% O2, suggesting a dose-dependent response as well as additive effects of hypercapnic and hypoxic stimuli. We conclude that the PCR, when assessed by acute hypoxia, hyperoxia, or hypercapnia, is present and intact in CCHS children who are able to sustain adequate ventilation during wakefulness.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of acute and chronic acetazolamide on resting ventilation and ventilatory responses in men

1993 ◽  
Vol 74 (1) ◽  
pp. 230-237 ◽  
Author(s):  
E. R. Swenson ◽  
J. M. Hughes
Keyword(s):  
Metabolic Acidosis ◽  
Ventilatory Response ◽  
Minute Ventilation ◽  
Respiratory Acidosis ◽  
Acute Effects ◽  
Acid Base Balance ◽  
Ventilatory Control ◽  
Peripheral Chemoreceptor ◽  
Ventilatory Responses ◽  
Base Balance

The effects of acetazolamide (ACTZ) on ventilatory control are thought to be mediated by metabolic acidosis. However, carbonic anhydrase (CA) inhibition within brain and chemoreceptors and tissue respiratory acidosis may also be important. We compared the acute effects of ACTZ (tissue respiratory acidosis and tissue CA inhibition without metabolic acidosis) on ventilation and ventilatory control with chronic ACTZ (acute effects plus metabolic acidosis). Five men were studied 1 h after 500 mg iv ACTZ or 0.9% saline (acute effects) and also after three doses of ACTZ (500 mg po every 6 h; chronic effects). Minute ventilation (VE), steady-state hypercapnic ventilatory response (HCVR), and hypoxic ventilatory response (HVR) were measured with respiratory inductance plethysmography. Resting VE was increased equally by acute and chronic ACTZ. HCVR increased with chronic ACTZ in hyperoxia and even further in hypoxia. In contrast, acute ACTZ had no effect on the HCVR slope in hyperoxia and suppressed its augmentation by hypoxia. HVR was fully suppressed by acute ACTZ but unchanged with chronic ACTZ. ACTZ also slowed the rate of full ventilatory response to CO2. These findings show that CA inhibitors affect ventilatory control in a complex fashion, not only through changes in systemic acid-base balance but also by central and peripheral chemoreceptor inhibition.

Stress-induced attenuation of the hypercapnic ventilatory response in awake rats

2001 ◽  
Vol 90 (5) ◽  
pp. 1729-1735 ◽  
Author(s):  
Richard Kinkead ◽  
Lydie Dupenloup ◽  
Nadine Valois ◽  
Roumiana Gulemetova
Keyword(s):  
Control System ◽  
Immobilization Stress ◽  
Ventilatory Response ◽  
Minute Ventilation ◽  
Respiratory Control ◽  
Whole Body ◽  
Respiratory Homeostasis ◽  
Whole Body Plethysmography ◽  
Ventilatory Response To Hypoxia ◽  
Awake Rats

To test the hypothesis that stress alters the performance of the respiratory control system, we compared the acute (20 min) responses to moderate hypoxia and hypercapnia of rats previously subjected to immobilization stress (90 min/day) with responses of control animals. Ventilatory measurements were performed on awake rats using whole body plethysmography. Under baseline conditions, there were no differences in minute ventilation between stressed and unstressed groups. Rats previously exposed to immobilization stress had a 45% lower ventilatory response to hypercapnia (inspiratory CO2 fraction = 0.05) than controls. In contrast, stress exposure had no statistically significant effect on the ventilatory response to hypoxia (inspiratory O2 fraction = 0.12). Stress-induced attenuation of the hypercapnic response was associated with reduced tidal volume and inspiratory flow increases; the frequency and timing components of the response were not different between groups. We conclude that previous exposure to a stressful condition that does not constitute a direct challenge to respiratory homeostasis can elicit persistent (≥24 h) functional plasticity in the ventilatory control system.

scholarly journals Regulation of breathing pattern by IL-10

2019 ◽  
Vol 317 (1) ◽  
pp. R190-R202 ◽  
Author(s):  
Charoula Eleni Giannakopoulou ◽  
Adamantia Sotiriou ◽  
Maria Dettoraki ◽  
Michael Yang ◽  
Fotis Perlikos ◽  
...  
Keyword(s):  
Tidal Volume ◽  
Minute Ventilation ◽  
Control Of Breathing ◽  
Neonatal Rat ◽  
Whole Body ◽  
Wild Type ◽  
Rapid Shallow Breathing Index ◽  
Regulation Of Breathing ◽  
Shallow Breathing

Proinflammatory cytokines like interleukin-1β (IL-1β) affect the control of breathing. Our aim is to determine the effect of the anti-inflammatory cytokine IL-10 οn the control of breathing. IL-10 knockout mice (IL-10−/−, n = 10) and wild-type mice (IL-10+/+, n = 10) were exposed to the following test gases: hyperoxic hypercapnia 7% CO2-93% O2, normoxic hypercapnia 7% CO2-21% O2, hypoxic hypercapnia 7% CO2-10% O2, and hypoxic normocapnia 3% CO2-10% O2. The ventilatory function was assessed using whole body plethysmography. Recombinant mouse IL-10 (rIL-10; 10 μg/kg) was administered intraperitoneally to wild-type mice ( n = 10) 30 min before the onset of gas challenge. IL-10 was administered in neonatal medullary slices (10–30 ng/ml, n = 8). We found that IL-10−/−mice exhibited consistently increased frequency and reduced tidal volume compared with IL-10+/+mice during room air breathing and in all test gases (by 23.62 to 33.2%, P < 0.05 and −36.23 to −41.69%, P < 0.05, respectively). In all inspired gases, the minute ventilation of IL-10−/−mice was lower than IL-10+/+(by −15.67 to −22.74%, P < 0.05). The rapid shallow breathing index was higher in IL-10−/−mice compared with IL-10+/+mice in all inspired gases (by 50.25 to 57.5%, P < 0.05). The intraperitoneal injection of rIL-10 caused reduction of the respiratory rate and augmentation of the tidal volume in room air and also in all inspired gases (by −12.22 to −29.53 and 32.18 to 45.11%, P < 0.05, respectively). IL-10 administration in neonatal rat ( n = 8) in vitro rhythmically active medullary slice preparations did not affect either rhythmicity or peak amplitude of hypoglossal nerve discharge. In conclusion, IL-10 may induce a slower and deeper pattern of breathing.

Ventilatory response to transient hyperoxia in head injury hyperventilation

1980 ◽  
Vol 49 (1) ◽  
pp. 52-58 ◽  
Author(s):  
A. G. Leitch ◽  
J. E. McLennan ◽  
S. Balkenhol ◽  
R. L. McLaurin ◽  
R. G. Loudon
Keyword(s):  
Head Injury ◽  
Ventilatory Response ◽  
Minute Ventilation ◽  
Respiratory Control ◽  
Normal Subjects ◽  
Respiratory Alkalosis ◽  
Cerebral Injury ◽  
Peripheral Chemoreceptor ◽  
Male Patients ◽  
Almost All

We have measured breath-by-breath instantaneous minute ventilation (VIinst) before, during, and after the administration of 10 breaths of 100% oxygen to seven male patients with head injury hyperventilation. The patients were hypoxemic (PaO2 61.2 ± 6.3) and hypocapnic (PaCO2 26.6 ± 5.9) with a respiratory alkalosis (pH 7.53 ± 0.06) while breathing air. Following the oxygen VIinst fell on the average by 40 ± 12.7% from 16.06 ± 3.75 1.min-1 to a minimum of 9.73 ± 3.20 1.min-1 at 20.4 ± 2.9 s after the first breath of oxygen. In the majority of our hyperventilating patients, almost all of the resting hyperventilation could be abolished transiently by 100% oxygen. This fall in ventilation represents the peripheral chemoreceptor contribution to resting ventilation and is increased in the head injury patients in comparison with normal subjects breathing air or hypoxic gas mixtures, altitude-acclimatized subjects and patients who are hypoxic because of chronic bronchitis or interstitial lung disease. We suggest that the increased reflex hypoxic drive to ventilation found in our patients is secondary to their cerebral injury, resulting in a reduction of descending cortical inhibitory influences on the medullary respiratory control centers.

Calcium/calmodulin-dependent kinase II mediates critical components of the hypoxic ventilatory response within the nucleus of the solitary tract in adult rats

2005 ◽  
Vol 289 (3) ◽  
pp. R871-R876 ◽  
Author(s):  
Stephen R. Reeves ◽  
Edwin S. Carter ◽  
Shang Z. Guo ◽  
David Gozal
Keyword(s):  
Ventilatory Response ◽  
Minute Ventilation ◽  
Acute Hypoxia ◽  
Respiratory Frequency ◽  
Whole Body ◽  
Solitary Tract ◽  
Hypoxic Ventilatory Response ◽  
Adult Rats ◽  
Osmotic Pumps ◽  
Calcium Calmodulin Dependent

Calcium/calmodulin-dependent kinase II (CaMKII) is an ubiquitous second messenger that is highly expressed in neurons, where it has been implicated in some of the pathways regulating neuronal discharge as well as N-methyl-d-aspartate receptor-mediated synaptic plasticity. The full expression of the mammalian hypoxic ventilatory response (HVR) requires intact central relays within the nucleus of the solitary tract (NTS), and neural transmission of hypoxic afferent input is mediated by glutamatergic receptor activity, primarily through N-methyl-d-aspartate receptors. To examine the functional role of CaMKII in HVR, KN-93, a highly selective antagonist of CaMKII, was microinjected in the NTS via bilaterally placed osmotic pumps in freely behaving adult male Sprague-Dawley rats for 3 days. Vehicle-loaded osmotic pumps were surgically placed in control animals, and adequate placement of cannulas was ascertained for all animals. HVR was measured using whole body plethysmography during exposure to 10% O2-balance N2 for 20 min. Compared with control rats, KN-93 administration elicited marked attenuations of peak HVR (pHVR) but did not modify normoxic minute ventilation. Differences in pHVR were primarily attributable to diminished respiratory frequency recruitments during pHVR without significant differences in tidal volume. These findings indicate that CaMKII activation in the NTS mediates respiratory frequency components of the ventilatory response to acute hypoxia; however, CaMKII activity does not appear to underlie components of normoxic ventilation.

The affinity of hemoglobin for oxygen affects ventilatory responses in mutant mice with Presbyterian hemoglobinopathy

2003 ◽  
Vol 285 (4) ◽  
pp. R747-R753 ◽  
Author(s):  
Masahiko Izumizaki ◽  
Masakatsu Tamaki ◽  
Yo-ichi Suzuki ◽  
Michiko Iwase ◽  
Takuji Shirasawa ◽  
...  
Keyword(s):  
Minute Ventilation ◽  
Globin Gene ◽  
Open Circuit ◽  
Mutant Mice ◽  
Whole Body ◽  
Wild Type ◽  
Peripheral Tissues ◽  
Ventilatory Responses ◽  
Significant Difference ◽  
In The Wild

The purpose of this study was to test whether chronically enhanced O2 delivery to tissues, without arterial hyperoxia, can change acute ventilatory responses to hypercapnia and hypoxia. The effects of decreased hemoglobin (Hb)-O2 affinity on ventilatory responses during hypercapnia (0, 5, 7, and 9% CO2 in O2) and hypoxia (10 and 15% O2 in N2) were assessed in mutant mice expressing Hb Presbyterian (mutation in the β-globin gene, β108 Asn → Lys). O2 consumption during normoxia, measured via open-circuit methods, was significantly higher in the mutant mice than in wild-type mice. Respiratory measurements were conducted with a whole body, unrestrained, single-chamber plethysmograph under conscious conditions. During hypercapnia, there was no difference between the slopes of the hypercapnic ventilatory responses, whereas minute ventilation at the same levels of arterial PCO2 was lower in the Presbyterian mice than in the wild-type mice. During both hypoxic exposures, ventilatory responses were blunted in the mutant mice compared with responses in the wild-type mice. The effects of brief hyperoxia exposure (100% O2) after 10% hypoxia on ventilation were examined in anesthetized, spontaneously breathing mice with a double-chamber plethysmograph. No significant difference was found in ventilatory responses to brief hypoxia between both groups of mice, indicating possible involvement of central mechanisms in blunted ventilatory responses to hypoxia in Presbyterian mice. We conclude that chronically enhanced O2 delivery to peripheral tissues can reduce ventilation during acute hypercapnic and hypoxic exposures.

Changes in respiratory timing induced by hypercapnia in maturing rats

1999 ◽  
Vol 87 (2) ◽  
pp. 484-490 ◽  
Author(s):  
Jalal M. Abu-Shaweesh ◽  
Ismail A. Dreshaj ◽  
Agnes J. Thomas ◽  
Musa A. Haxhiu ◽  
Kingman P. Strohl ◽  
...  
Keyword(s):  
Ventilatory Response ◽  
Minute Ventilation ◽  
Aminobutyric Acid ◽  
Whole Body ◽  
Sprague Dawley ◽  
Newborn Rat ◽  
Rat Pups ◽  
Significant Prolongation ◽  
Sprague Dawley Rats ◽  
Central Origin

Premature infants respond to hypercapnia by an attenuated ventilatory response that is characterized by a decrease in respiratory frequency. We hypothesized that this impaired hypercapnic ventilatory response is of central origin and is mediated via γ-aminobutyric acid-ergic (GABAergic) pathways. We therefore studied two groups of maturing Sprague-Dawley rats: unrestrained rats in a whole body plethysmograph at four postnatal ages (5, 16–17, 22–23, and 41–42 days); and ventilated, decerebrate, vagotomized, paralyzed rats in which phrenic nerve responses to hypercapnia were measured at 4–6 and 37–39 days of age. In the unrestrained group, the increase in minute ventilation induced by hypercapnia was significantly lower at 5 days vs. beyond 16 days. Although there was an increase in tidal volume at all ages, frequency decreased significantly from baseline at 5 days, whereas it increased significantly at 16–17, 22–23, and 41–42 days. The decrease in frequency at 5 days of age was mainly due to a significant prolongation in expiratory duration (Te). In the ventilated group, hypercapnia also caused prolongation in Te at 4–6 days but not at 37–39 days of age. Intravenous administration of bicuculline (GABAA-receptor blocker) abolished the prolongation of Te in response to hypercapnia in the newborn rats. We conclude that newborn rat pups exhibit a characteristic ventilatory response to CO2 expressed as a centrally mediated prolongation of Te that appears to be mediated by GABAergic mechanisms.

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