scholarly journals Acclimatization of low altitude-bred deer mice (Peromyscus maniculatus) to high altitude

2018 ◽  
Vol 125 (5) ◽  
pp. 1411-1423 ◽  
Author(s):  
D. Merrill Dane ◽  
Khoa Cao ◽  
Hua Lu ◽  
Cuneyt Yilmaz ◽  
Jamie Dolan ◽  
...  
Keyword(s):  
Blood Flow ◽  
High Altitude ◽  
Lung Volume ◽  
Pulmonary Blood Flow ◽  
Peromyscus Maniculatus ◽  
Deer Mice ◽  
Alveolar Type ◽  
Type I ◽  
Lower Altitude ◽  
Lung Expansion

A colony of deer mice subspecies ( Peromyscus maniculatus sonoriensis) native to high altitude (HA) has been maintained at sea level for 18–20 generations and remains genetically unchanged. To determine if these animals retain responsiveness to hypoxia, one group (9–11 wk old) was acclimated to HA (3,800 m) for 8 wk. Age-matched control animals were acclimated to a lower altitude (LA; 252 m). Maximal O2 uptake (V̇o2max) was measured at the respective altitudes. On a separate day, lung volume, diffusing capacity for carbon monoxide (DLCO), and pulmonary blood flow were measured under anesthesia using a rebreathing technique at two inspired O2 tensions. The HA-acclimated deer mice maintained a normal V̇o2max relative to LA baseline. Compared with LA control mice, antemortem lung volume was larger in HA mice in a manner dependent on alveolar O2 tension. Systemic hematocrit, pulmonary blood flow, and standardized DLCO did not differ significantly between groups. HA mice showed a higher postmortem alveolar-capillary hematocrit, larger alveolar ducts, and smaller distal conducting structures. In HA mice, absolute volumes of alveolar type I epithelia and endothelia were higher whereas that of interstitia was lower than in LA mice. These structural changes occurred without a net increase in whole-lung septal tissue-capillary volumes or surface areas. Thus, deer mice bred and raised to adulthood at LA retain phenotypic plasticity and adapt to HA without a decrement in V̇o2max via structural (enlarged airspaces, alveolar septal remodeling) and nonstructural (lung expansion under hypoxia) mechanisms and without an increase in systemic hematocrit or compensatory lung growth. NEW & NOTEWORTHY Deer mice ( Peromyscus maniculatus) are robust and very active mammals that are found across the North American continent. They are also highly adaptable to extreme environments. When introduced to high altitude they retain remarkable adaptive ability to the low-oxygen environment via lung expansion and remodeling of existing lung structure, thereby maintaining normal aerobic capacity without generating more red blood cells or additional lung tissue.

Alveolar diffusion-perfusion interactions during high-altitude residence in guinea pigs

2007 ◽  
Vol 102 (6) ◽  
pp. 2179-2185 ◽  
Author(s):  
Cuneyt Yilmaz ◽  
D. Merrill Dane ◽  
Connie C. W. Hsia
Keyword(s):  
Carbon Monoxide ◽  
Blood Flow ◽  
High Altitude ◽  
Lung Volume ◽  
Guinea Pigs ◽  
Pulmonary Blood Flow ◽  
Ultrastructural Changes ◽  
Diffusing Capacity ◽  
Adaptive Responses ◽  
Structural Adaptation

We previously reported in weanling guinea pigs raised at high altitude (HA; 3,800 m) an elevated lung diffusing capacity estimated by morphometry from alveolar-capillary surface area, harmonic mean blood-gas barrier thickness, and pulmonary capillary blood volume (Vc) compared with litter-matched control animals raised at an intermediate altitude (IA; 1,200 m) (Hsia CCW, Polo Carbayo JJ, Yan X, Bellotto DJ. Respir Physiol Neurobiol 147: 105–115, 2005). To determine if HA-induced alveolar ultrastructural changes are associated with improved alveolar function, we measured lung diffusing capacity for carbon monoxide (DlCO), membrane diffusing capacity for carbon monoxide (DmCO), Vc, pulmonary blood flow, and lung volume by a rebreathing technique in litter-matched male weanling Hartley guinea pigs raised at HA or IA for 4 or 12 mo. Separate control animals were also raised and studied at sea level (SL). Resting measurements were obtained in the conscious nonsedated state. In HA animals compared with corresponding IA or SL controls, lung volume and hematocrit were significantly higher while pulmonary blood flow was lower. At a given pulmonary blood flow, DlCO and DmCO were higher in HA-raised animals than in control animals without a significant change in Vc. We conclude that 1) HA residence enhanced physiological diffusing capacity corresponding to that previously estimated on the basis of structural adaptation, 2) adaptation in diffusing capacity and its components should be interpreted with respect to pulmonary blood flow, and 3) this noninvasive rebreathing technique could be used to follow adaptive responses in small animals.

The effects of artificial lung inflation on pulmonary blood flow and heart rate in the turtle Trachemys scripta.

1997 ◽  
Vol 200 (19) ◽  
pp. 2539-2545
Author(s):  
J Herman ◽  
T Wang ◽  
A W Smits ◽  
J W Hicks
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Lung Volume ◽  
Pulmonary Blood Flow ◽  
Trachemys Scripta ◽  
Spontaneous Ventilation ◽  
Lung Inflation ◽  
Cardiovascular Changes ◽  
Blood Flows ◽  
Stimulation Of

As for most ectothermic vertebrates, the breathing pattern of turtles is episodic, and pulmonary blood flow (Qpul) and heart rate (fH) normally increase several-fold during spontaneous ventilation. While some previous studies suggest that these cardiovascular changes are caused by stimulation of pulmonary stretch receptors (PSRs) during ventilation, it has been noted in other studies that blood flows often change prior to the initiation of breathing. Given the uncertainty regarding the role of PSRs in the regulation of central vascular blood flows, we examined the effect of manipulating lung volume (and therefore PSR stimulation) on blood flows and heart rate in the freshwater turtle Trachemys scripta. Turtles were instrumented with blood flow probes on the left aortic arch and the left pulmonary artery for measurements of blood flow, and catheters were inserted into both lungs for manipulation of lung volume. In both anaesthetized and fully recovered animals, reductions or increases in lung volume by withdrawal of lung gas or injection of air, N2, O2 or 10% CO2 (in room air) had no effect on blood flows. Furthermore, simulations of normal breathing bouts by withdrawal and injection of lung gas did not alter Qpul or fH. We conclude that stimulation of PSRs is not sufficient to elicit cardiovascular changes and that the large increase in Qpul and fH normally observed during spontaneous ventilation are probably caused by a simultaneous feedforward control of central origin.

Regional Distribution of Pulmonary Blood Flow in Normal High-Altitude Dwellers at 3,650 m (12,200 ft)

Respiration ◽  
1975 ◽  
Vol 32 (3) ◽  
pp. 189-209 ◽  
Author(s):  
J. Coudert ◽  
M. Paz-Zamora ◽  
L. Barragan ◽  
L. Briançon ◽  
H. Spielvogel ◽  
...  
Keyword(s):  
Blood Flow ◽  
High Altitude ◽  
Pulmonary Blood Flow ◽  
Regional Distribution

scholarly journals Development of homeothermic endothermy is delayed in high-altitude native deer mice ( Peromyscus maniculatus)

2019 ◽  
Vol 286 (1907) ◽  
pp. 20190841 ◽  
Author(s):  
Cayleih E. Robertson ◽  
Glenn J. Tattersall ◽  
Grant B. McClelland
Keyword(s):  
High Altitude ◽  
Peromyscus Maniculatus ◽  
Common Garden ◽  
Deer Mice ◽  
Ambient Temperatures ◽  
Equivalent Age ◽  
Brown Adipose ◽  
Challenging Environment ◽  
Sympathetic Regulation ◽  
Saving Measure

Altricial mammals begin to independently thermoregulate during the first few weeks of postnatal development. In wild rodent populations, this is also a time of high mortality (50–95%), making the physiological systems that mature during this period potential targets for selection. High altitude (HA) is a particularly challenging environment for small endotherms owing to unremitting low O 2 and ambient temperatures. While superior thermogenic capacities have been demonstrated in adults of some HA species, it is unclear if selection has occurred to survive these unique challenges early in development. We used deer mice ( Peromyscus maniculatus ) native to high and low altitude (LA), and a strictly LA species ( Peromyscus leucopus ), raised under common garden conditions, to determine if postnatal onset of endothermy and maturation of brown adipose tissue (BAT) is affected by altitude ancestry. We found that the onset of endothermy corresponds with the maturation and activation of BAT at an equivalent age in LA natives, with 10-day-old pups able to thermoregulate in response to acute cold in both species. However, the onset of endothermy in HA pups was substantially delayed (by approx. 2 days), possibly driven by delayed sympathetic regulation of BAT. We suggest that this delay may be part of an evolved cost-saving measure to allow pups to maintain growth rates under the O 2 -limited conditions at HA.

Differential effect of recruitment maneuvres on pulmonary blood flow and oxygenation during HFOV in preterm lambs

2008 ◽  
Vol 105 (2) ◽  
pp. 603-610 ◽  
Author(s):  
Graeme R. Polglase ◽  
Timothy J. M. Moss ◽  
Ilias Nitsos ◽  
Beth J. Allison ◽  
J. Jane Pillow ◽  
...  
Keyword(s):  
Blood Flow ◽  
Lung Volume ◽  
Airway Pressure ◽  
Pulmonary Blood Flow ◽  
Ductus Arteriosus ◽  
Oxygenation Index ◽  
Preterm Neonates ◽  
Mean Airway Pressure ◽  
Lung Volume Recruitment ◽  
High Frequency Oscillatory

The effects of lung volume recruitment manouvres on pulmonary blood flow (PBF) during high-frequency oscillatory ventilation (HFOV) in preterm neonates are unknown. Since increased airway pressure adversely affects PBF, we compared the effects of two HFOV recruitment strategies on PBF and oxygenation index (OI). Preterm lambs (128 ± 1 day gestation; term ∼150 days) were anesthetized and ventilated using HFOV (10 Hz, 33% tI) with a mean airway pressure (Pao) of 15 cmH2O. Lung volume was recruited by either increasing Pao to 25 cmH2O for 1 min, repeated five times at 5-min intervals (Sigh group; n = 5) or stepwise (5 cmH2O) changes in Pao at 5-min intervals incrementing up to 30 cmH2O then decrementing back to 15 cmH2O (Ramp group; n = 6). Controls ( n = 5) received constant HFOV at 15 cmH2O. PBF progressively decreased (by 45 ± 4%) and OI increased (by 15 ± 6%, indicating reduced oxygenation) in controls during HFOV, which was similar to the changes observed in the Sigh group of lambs. In the Ramp group, PBF fell (by 54 ± 10%) as airway pressure increased ( r2 = 0.99), although the PBF did not increase again as the Pao was subsequently reduced. The OI decreased (by 47 ± 9%), reflecting improved oxygenation at high Pao levels during HFOV in the Ramp group. However, high Pao restored retrograde PBF during diastole in four of six lambs, indicating the restoration of right-to-left shunting through the ductus arteriosus. Thus the choice of volume recruitment maneuvre influences the magnitude of change in OI and PBF that occurs during HFOV. Despite significantly improving OI, the ramp recruitment approach causes sustained changes in PBF.

Influence of Anaesthesia on the Regional Distribution of Perfusion and Ventilation in the Lung

1970 ◽  
Vol 38 (4) ◽  
pp. 451-460 ◽  
Author(s):  
G. H. Hulands ◽  
R. Greene ◽  
L. D. Iliff ◽  
J. F. Nunn
Keyword(s):  
Blood Flow ◽  
Lung Volume ◽  
Pulmonary Blood Flow ◽  
Artificial Ventilation ◽  
Pulmonary Ventilation ◽  
Regional Distribution ◽  
Residual Capacity ◽  
Arterial Po2 ◽  
Ventilation And Perfusion ◽  
Perfusion Unit

1. Distribution of lung volume, pulmonary ventilation and perfusion were studied in supine patients before and during anaesthesia with paralysis and artificial ventilation. Inspired gas and pulmonary blood flow were measured with 133xenon and the chest was scanned with vertically moving counters at a lung volume of 1 litre above functional residual capacity. 2. Ventilation/unit lung volume was slightly greater and perfusion/unit lung volume substantially greater during anaesthesia in the dependent parts of the lungs. The spread of ventilation/perfusion ratios in supine conscious patients was small in comparison with that reported in upright conscious patients. During anaesthesia and artificial ventilation, the inequality of ventilation to perfusion was marginally increased in three of the four patients. 3. Ventilation/perfusion inequality alone was insufficient to explain the alveolar—arterial Po2 difference usually observed during anaesthesia.

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