scholarly journals Ventilatory responses to ozone are reduced in immature rats

2000 ◽  
Vol 88 (6) ◽  
pp. 2023-2030 ◽  
Author(s):  
S. A. Shore ◽  
J. H. Abraham ◽  
I. N. Schwartzman ◽  
G. G. Krishna Murthy ◽  
J. D. Laporte
Keyword(s):  
Bronchoalveolar Lavage ◽  
Ventilatory Response ◽  
Minute Ventilation ◽  
Sprague Dawley ◽  
Adult Rats ◽  
Ventilatory Responses ◽  
Sprague Dawley Rats ◽  
Immature Rats ◽  
Old Rats ◽  
Induced Changes

During ozone (O3) exposure, adult rats decrease their minute ventilation (V˙e). To determine whether such changes are also observed in immature animals, Sprague-Dawley rats, aged 2, 4, 6, 8, or 12 wk, were exposed to O3(2 ppm) in nose-only-exposure plethysmographs. BaselineV˙e normalized for body weight decreased with age from 2.1 ± 0.1 ml ⋅ min−1⋅ g−1in 2-wk-old rats to 0.72 ± 0.03 ml ⋅ min−1⋅ g−1in 12-wk-old rats, consistent with the higher metabolic rates of younger animals. In adult (8- and 12-wk-old) rats, O3caused 40–50% decreases in V˙e that occurred primarily as the result of a decrease in tidal volume. In 6-wk-old rats, O3-induced changes inV˙e were significantly less, and in 2- and 4-wk-old rats, no significant changes inV˙e were observed during O3exposure. The increased baseline V˙e and the smaller decrements in V˙e induced by O3in the immature rats imply that their delivered dose of O3is much higher than in adult rats. To determine whether these differences in O3dose influence the extent of injury, we measured bronchoalveolar lavage protein concentrations. The magnitude of the changes in bronchoalveolar lavage induced by O3was significantly greater in 2- than in 8-wk-old rats (267 ± 47 vs. 165 ± 22%, respectively, P < 0.05). O3exposure also caused a significant increase in PGE2in 2-wk-old but not in adult rats. The results indicate that the ventilatory response to O3is absent in 2-wk-old rats and that lack of this response, in conjunction with a greater specific ventilation, leads to greater lung injury.

Kinetic impairment of nitrogen and muscle glutamine metabolisms in old glucocorticoid-treated rats

1999 ◽  
Vol 276 (3) ◽  
pp. E558-E564 ◽  
Author(s):  
Regine Minet-Quinard ◽  
Christophe Moinard ◽  
Françoise Villie ◽  
Stephane Walrand ◽  
Marie-Paule Vasson ◽  
...  
Keyword(s):  
Control Group ◽  
Synthetase Activity ◽  
Aged Rats ◽  
Sprague Dawley ◽  
Adult Rats ◽  
Glucocorticoid Treatment ◽  
Sprague Dawley Rats ◽  
End Of Treatment ◽  
Catabolic State ◽  
Old Rats

Aged rats are more sensitive to injury, possibly through an impairment of nitrogen and glutamine (Gln) metabolisms mediated by glucocorticoids. We studied the metabolic kinetic response of adult and old rats during glucocorticoid treatment. The male Sprague-Dawley rats were 24 or 3 mo old. Both adult and old rats were divided into 7 groups. Groups labeled G3, G5, and G7 received, by intraperitoneal injection, 1.50 mg/kg of dexamethasone (Dex) for 3, 5, and 7 days, respectively. Groups labeled G3PF, G5PF, and G7PF were pair fed to the G3, G5, or G7 groups and were injected with an isovolumic solution of NaCl. One control group comprised healthy rats fed ad libitum. The response to aggression induced specifically by Dex (i.e., allowing for variations in pair-fed controls) appeared later in the aged rats (decrease in nitrogen balance from day 1 in adults but only from day 4 in old rats). The adult rats rapidly adapted to Dex treatment, whereas the catabolic state worsened until the end of treatment in the old rats. Gln homeostasis was not maintained in the aged rats; despite an early increase in muscular Gln synthetase activity, the Gln pool was depleted. These results suggest a kinetic impairment of both nitrogen and muscle Gln metabolisms in response to Dex with aging.

scholarly journals Potentiation of hypoxic ventilatory response by hyperoxia in the conscious rat: putative role of nitric oxide

1998 ◽  
Vol 85 (1) ◽  
pp. 129-132 ◽  
Author(s):  
David Gozal
Keyword(s):  
Nitric Oxide ◽  
Ventilatory Response ◽  
Minute Ventilation ◽  
Hypoxic Ventilatory Response ◽  
Sprague Dawley ◽  
Conscious Rat ◽  
Adult Rats ◽  
Hyperoxic Exposure ◽  
Essential Components ◽  
Oxide Synthase

In humans, the hypoxic ventilatory response (HVR) is augmented when preceded by a short hyperoxic exposure (Y. Honda, H. Tani, A. Masuda, T. Kobayashi, T. Nishino, H. Kimura, S. Masuyama, and T. Kuriyama. J. Appl. Physiol. 81: 1627–1632, 1996). To examine whether neuronal nitric oxide synthase (nNOS) is involved in such hyperoxia-induced HVR potentiation, 17 male Sprague-Dawley adult rats underwent hypoxic challenges (10% O2-5% CO2-balance N2) preceded either by 10 min of room air (−O2) or of 100% O2(+O2). At least 48 h later, similar challenges were performed after the animals received the selective nNOS inhibitor 7-nitroindazole (25 mg/kg ip). In −O2 runs, minute ventilation (V˙e) increased from 121.3 ± 20.5 (SD) ml/min in room air to 191.7 ± 23.8 ml/min in hypoxia ( P< 0.01). After +O2,V˙e increased from 114.1 ± 19.8 ml/min in room air to 218.4 ± 47.0 ml/min in hypoxia (+O2 vs. −O2: P < 0.005, ANOVA). After 7-nitroindazole administration, HVR was not affected in the −O2 treatment group withV˙e increasing from 113.7 ± 17.8 ml/min in room air to 185.8 ± 35.0 ml/min in hypoxia ( P < 0.01). However, HVR potentiation in +O2-exposed animals was abolished (111.8 ± 18.0 ml/min in room air to 184.1 ± 35.6 ml/min in hypoxia; +O2 vs. −O2: P not significant). We conclude that in the conscious rat nNOS activation mediates essential components of the HVR potentiation elicited by a previous short hyperoxic exposure.

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.

A potential early physiological marker for CNS oxygen toxicity: hyperoxic hyperpnea precedes seizure in unanesthetized rats breathing hyperbaric oxygen

2013 ◽  
Vol 114 (8) ◽  
pp. 1009-1020 ◽  
Author(s):  
Raffaele Pilla ◽  
Carol S. Landon ◽  
Jay B. Dean
Keyword(s):  
Hyperbaric Oxygen ◽  
Ventilatory Response ◽  
Minute Ventilation ◽  
Phase 1 ◽  
Oxygen Toxicity ◽  
Sprague Dawley ◽  
Hyperbaric Chamber ◽  
Phase 3 ◽  
Sprague Dawley Rats ◽  
Animal Chamber

Hyperbaric oxygen (HBO2) stimulates presumptive central CO2-chemoreceptor neurons, increases minute ventilation (V̇min), decreases heart rate (HR) and, if breathed sufficiently long, produces central nervous system oxygen toxicity (CNS-OT; i.e., seizures). The risk of seizures when breathing HBO2 is variable between individuals and its onset is difficult to predict. We have tested the hypothesis that a predictable pattern of cardiorespiration precedes an impending seizure when breathing HBO2. To test this hypothesis, 27 adult male Sprague-Dawley rats were implanted with radiotelemetry transmitters to assess diaphragmatic/abdominal electromyogram, electrocardiogram, and electroencephalogram. Seven days after surgery, each rat was placed in a sealed, continuously ventilated animal chamber inside a hyperbaric chamber. Both chambers were pressurized in parallel using poikilocapnic 100% O2 (animal chamber) and air (hyperbaric chamber) to 4, 5, or 6 atmospheres absolute (ATA). Breathing 1 ATA O2 initially decreased V̇min and HR ( Phase 1 of the compound hyperoxic ventilatory response). With continued exposure to normobaric hyperoxia, however, V̇min began increasing toward the end of exposure in one-third of the animals tested. Breathing HBO2 induced an early transient increase in V̇min ( Phase 2) and HR during the chamber pressurization, followed by a second significant increase of V̇min ≤8 min prior to seizure ( Phase 3). HR, which subsequently decreased during sustained hyperoxia, showed no additional changes prior to seizure. We conclude that hyperoxic hyperpnea ( Phase 3 of the compound hyperoxic ventilatory response) is a predictor of an impending seizure while breathing poikilocapnic HBO2 at rest in unanesthetized rats.

scholarly journals The development of arylsulphatase in the small intestine of the rat

1969 ◽  
Vol 114 (2) ◽  
pp. 343-350 ◽  
Author(s):  
S. H. Danovitch ◽  
L. Laster
Keyword(s):  
Small Intestine ◽  
Specific Activity ◽  
Sprague Dawley ◽  
Adult Rats ◽  
Ph Optimum ◽  
Distal Small Intestine ◽  
Sprague Dawley Rats ◽  
Proximal Small Intestine ◽  
Liver And Kidney ◽  
Old Rats

1. Arylsulphatase activity was measured in stomach, proximal and distal third of small intestine, colon, liver and kidney of foetal and neonatal Sprague–Dawley rats and Swiss mice, with nitrocatechol sulphate as substrate. 2. The specific activity in the distal small intestine, but not in the stomach, proximal small intestine or colon, increased about fourfold between 5 and 16 days after birth in both conventional and germ-free rats. 3. No comparable increase occurred in the distal small intestine of the mouse. 4. The specific activity of acid phosphatase in the distal small intestine of the rat rose only slightly when the arylsulphatase activity increased. 5. The pH optimum and Michaelis constant of arylsulphatase activity of the distal small intestine were similar for 1-day-old, 9-day-old and adult rats. 6. When extracts of distal small intestine of 1-day-old and 9-day-old rats were incubated together, the arylsulphatase activities were additive.

Cardiac output in adult and neonatal rats utilizing impedance cardiography

1987 ◽  
Vol 253 (5) ◽  
pp. H1298-H1304
Author(s):  
R. W. Gotshall ◽  
J. C. Breay-Pilcher ◽  
B. D. Boelcskevy
Keyword(s):  
Cardiac Output ◽  
Impedance Cardiography ◽  
Small Animals ◽  
Neonatal Rats ◽  
Sprague Dawley ◽  
Adult Rats ◽  
Sprague Dawley Rats ◽  
Head Up Tilt ◽  
Old Rats ◽  
Preload Reduction

Impedance cardiography (IC) has the potential to be applied to very small animals for the measurement of cardiac output (Q). To evaluate this, Q measured by impedance (ZQ) and thermal dilution (TDQ) were compared in adult Sprague-Dawley rats. Absolute values for TDQ were comparable with ZQ (e.g., 29.7 vs. 26.0 ml.min-1.100 g-1), and both equally followed the change in Q caused by hemorrhage and reinfusion of blood. IC was also evaluated in neonatal rats (1 and 7 day old). Control ZQ values were 113 ml.min-1.100 g-1 for the 1-day-old rats, and 104 ml.min-1.100 g-1 for 7-day-old rats. Both stroke volume and Q decreased with head-up tilt and increased with head-down tilt for both ages. Therefore, in the neonate, ZQ decreased appropriately with age and with preload reduction. From these results, it is concluded that IC can be utilized to evaluate cardiac function in neonatal and adult rats.

Ventilatory responses to hypoxia and hypercapnia in awake rats pretreated with capsaicin

1991 ◽  
Vol 70 (3) ◽  
pp. 1168-1174 ◽  
Author(s):  
G. T. De Sanctis ◽  
F. H. Green ◽  
J. E. Remmers
Keyword(s):  
Ventilatory Response ◽  
Minute Ventilation ◽  
Group Analysis ◽  
Treated Group ◽  
Adult Rats ◽  
Ventilatory Responses ◽  
C Fibers ◽  
Afferent Fibers ◽  
Primary Afferent Fibers ◽  
Respiratory Phases

Ventilatory responses to hypoxia and hypercapnia were measured by indirect plethysmography in unanesthetized unrestrained adult rats injected neonatally with capsaicin (50 mg/kg) or vehicle. Such capsaicin treatment ablates a subpopulation of primary afferent fibers containing substance P and various other neuropeptides. Ventilation was measured while the rats breathed air, 12% O2 in N2, 8% O2 in N2, 5% CO2 in O2, or 8% CO2 in O2. Neonatal treatment with capsaicin caused marked alterations in both the magnitude and composition of the hypoxic but not hypercapnic ventilatory response. The increase in minute ventilation evoked by hypoxia in the vehicle-treated rats resulted entirely from an increase in respiratory frequency. In the capsaicin-treated rats the hypoxic ventilatory response was significantly reduced owing to an attenuation of the frequency response. Although both groups responded to hypoxia with a shortening in inspiratory and expiratory times, rats treated with capsaicin displayed less shortening of both respiratory phases. By contrast, hypercapnia induced a brisk ventilatory response in the capsaicin-treated group that was similar in magnitude and pattern to that observed in the vehicle-treated group. Analysis of the components of the hypercapnic ventilatory responses revealed no significant differences between the two groups. We, therefore, conclude that neuropeptide-containing C-fibers are essential for the tachypnic component of the ventilatory response to hypoxia but not hypercapnia.

scholarly journals Chronic hyperoxia alters the early and late phases of the hypoxic ventilatory response in neonatal rats

2010 ◽  
Vol 109 (3) ◽  
pp. 796-803 ◽  
Author(s):  
Ryan W. Bavis ◽  
Kristen M. Young ◽  
Kevin J. Barry ◽  
Matthew R. Boller ◽  
Eugene Kim ◽  
...  
Keyword(s):  
Ventilatory Response ◽  
Acute Hypoxia ◽  
Pulmonary Ventilation ◽  
Respiratory Control ◽  
Hypoxic Ventilatory Response ◽  
Sprague Dawley ◽  
Adult Rats ◽  
Sprague Dawley Rats ◽  
The Central Nervous System ◽  
Peripheral Arterial

Chronic hyperoxia during the first 1–4 postnatal weeks attenuates the hypoxic ventilatory response (HVR) subsequently measured in adult rats. Rather than focusing on this long-lasting plasticity, the present study considered the influence of hyperoxia on respiratory control during the neonatal period. Sprague-Dawley rats were born and raised in 60% O2 until studied at postnatal ages (P) of 4, 6–7, or 13–14 days. Ventilation and metabolism were measured in normoxia (21% O2) and acute hypoxia (12% O2) using head-body plethysmography and respirometry, respectively. Compared with age-matched rats raised in room air, the major findings were 1) diminished pulmonary ventilation and metabolic O2 consumption in normoxia at P4 and P6–7; 2) decreased breathing stability during normoxia; 3) attenuation of the early phase of the HVR at P6–7 and P13–14; and 4) a sustained increase in ventilation during hypoxia (vs. the normal biphasic HVR) at all ages studied. Attenuation of the early HVR likely reflects progressive impairment of peripheral arterial chemoreceptors while expression of a sustained HVR in neonates before P7 suggests that hyperoxia also induces plasticity within the central nervous system. Together, these results suggest a complex interaction between inhibitory and excitatory effects of hyperoxia on the developing respiratory control system.

Light and electron microscopic investigation of adenohypophyses of germfree, food-restricted, and germfree-food restricted aging, male lobund-wistar rats

1988 ◽  
Vol 46 ◽  
pp. 352-353
Author(s):  
G. Ilse ◽  
K. Kovacs ◽  
N. Ryan ◽  
T. Sano ◽  
L. Stefaneanu ◽  
...  
Keyword(s):  
Wistar Rats ◽  
Microscopic Investigation ◽  
Electron Microscopic Investigation ◽  
Aging Male ◽  
Sprague Dawley ◽  
Electron Microscopic ◽  
Sprague Dawley Rats ◽  
Old Rats ◽  
Ad Libitum ◽  
Microscopic Findings

Germfree state and food restriction have been shown to increase life span and delay tumor occurrence in rats. We report here the histologic, immunocytochemical and electron microscopic findings of adenohypophyses of aging, male Lobund-Wistar rats raised at Lobund Laboratories. In our previous study, the morphologic changes in the adenohypophyses of old rats have been extensively investigated by histology, immunocytochemistry and electron microscopy. Lactotroph adenomas were frequent in Long-Evans and Sprague-Dawley rats, whereas gonadotroph adenomas were frequent in Sprague-Dawley and Wistar rats.Male Lobund-Wistar rats were divided into four groups: 1) conventional, which were raised under normal non-germfree environment and received food ad libitum; 2) germfree-food ad libitum; 3) conventional environment-food restricted and 4) germfree-food restricted. The adenohypophyses were removed from 6-month-, 18-month- and 30-month-old rats. For light microscopy, adenohypophyses were fixed in formalin and embedded in paraffin.

Sexual influence on the control of breathing

1983 ◽  
Vol 54 (4) ◽  
pp. 874-879 ◽  
Author(s):  
D. P. White ◽  
N. J. Douglas ◽  
C. K. Pickett ◽  
J. V. Weil ◽  
C. W. Zwillich
Keyword(s):  
Ventilatory Response ◽  
Minute Ventilation ◽  
Premenopausal Women ◽  
Co2 Production ◽  
Menstrual Phase ◽  
Co2 Partial Pressure ◽  
Ventilatory Responses ◽  
Chemical Stimuli ◽  
Low Levels ◽  
Normal Women

Previous investigation has demonstrated that progesterone, a hormone found in premenopausal women, is a ventilatory stimulant. However, fragmentary data suggest that normal women may have lower ventilatory responses to chemical stimuli than men, in whom progesterone is found at low levels. As male-female differences have not been carefully studied, we undertook a systematic comparison of resting ventilation and ventilatory responses to chemical stimuli in men and women. Resting ventilation was found to correlate closely with CO2 production in all subjects (r = 0.71, P less than 0.001), but women tended to have a greater minute ventilation per milliliter of CO2 produced (P less than 0.05) and consequently a lower CO2 partial pressure (PCO2) (men 35.1 +/- 0.5 Torr, women 33.2 +/- 0.5 Torr; P less than 0.02). Women were also found to have lower tidal volumes, even when corrected from body surface area (BSA), and greater respiratory frequency than comparable males. The hypoxic ventilatory response (HVR) quantitated by the shape parameter A was significantly greater in men [167 +/- 22 (SE)] than in women (109 +/- 13; P less than 0.05). In men this hypoxic response was found to correlate closely with O2 consumption (r = 0.75, P less than 0.001) but with no measure of size or metabolic rate in women. The hypercapnic ventilatory response, expressed as the slope of ventilation vs. PCO2, was also greater in men (2.30 +/- 0.23) than in women (1.58 +/- 0.19, P less than 0.05). Finally women tended to have higher ventilatory responses in the luteal than in the follicular menstrual phase, but this was significant only for HVR (P less than 0.05). Women, with relatively higher resting ventilation, have lower responses to hypoxia and hypercapnia.

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