Cardiovascular adjustments to acute hypoxemia superimposed on chronic hypoxemia in lambs

Dalinghaus, Michiel; Gratama, Jan W.; Zijlstra, W. G.; Kuipers, Jrg

doi:10.1152/ajpheart.1995.268.3.h974

Cited by 1 publication

(1 citation statement)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our findings indicate that post-CBD, lambs are better able to withstand thermal and hypoxic challenges with increasing postnatal age although they are dependent on a decreased thermometabolic rather than a ventilatory response in order to achieve this. It should also be noted that the cardiovascular response to acute hypoxaemia superimposed on chronic hypoxaemia is similar to that of normoxic lambs (Dalinghaus et al 1995), and is unaffected by alveolar hypercapnia in CBD lambs (Fewell et al 1989).…”

Section: Statistical Analysesmentioning

confidence: 84%

The Influence of Acute Hypoxia and Carotid Body Denervation on Thermoregulation During Non‐Rapid Eye Movement Sleep in the Developing Lamb

Symonds

Andrews

Johnson

1999

Experimental Physiology

View full text Add to dashboard Cite

summaryWe investigated the influence of ambient temperature on the thermoregulatory response to hypoxia in developing lambs before (at 4 and 14 days of age) and after (17 and 30 days of age) carotid body denervation (CBD). Lambs were studied during non-rapid eye movement sleep at thermoneutral (23-15°C) and cool (10-5°C) ambient temperatures, during normoxia and acute hypoxia (inspired oxygen content of 13%). Measurements of oxygen consumption, arterial partial pressures of Oµ and COµ, colonic temperature, incidence of shivering and plasma concentrations of thyroid hormones, cortisol, insulin and glucose were made under each condition. Oxygen consumption was higher at cool compared with thermoneutral ambient temperatures and decreased during hypoxia during cooling at all stages. At 4 days of age, only one lamb shivered during cooling in normoxia, but 4 out of 12 lambs shivered during hypoxia and colonic temperature fell, significantly, by 0·2°C. At 14 days, 8 out of 12 lambs shivered during cooling, of which 6 continued to shiver during hypoxia but colonic temperature did not change significantly. Plasma triiodothyronine concentrations increased on cooling at 4 and 14 days, an affect that was inhibited by hypoxia at 4, but not 14 days of age. At 17 days of age, i.e. post-CBD, plasma thyroid hormone concentrations and oxygen consumption were lower during cold exposure compared with intact lambs at 14 days of age. In CBD lambs, imposing further hypoxia resulted in colonic temperature falling 0·6°C during cooling, with only 2 out of 10 lambs shivering. Plasma glucose and insulin, but not cortisol, concentrations decreased during hypoxia, irrespective of age or CBD. It is concluded that hypoxia has an important influence on metabolism and thermoregulation, which is modulated by age and environmental conditions. Compromised carotid body function, in lambs older than 2 weeks of age, can result in severe hypoxia and thermoregulatory dysfunction even with modest environmental cooling.

show abstract

Section: Statistical Analysesmentioning

confidence: 84%