Document Detail

The respiratory response of the new-born lamb to inhaled CO-2 with and without accompanying hypoxia.
MedLine Citation:
PMID:  5965899     Owner:  NLM     Status:  MEDLINE    
1. The respiratory response to inhaled CO(2) was measured in twenty unanaesthetized new-born lambs aged 4 hr-10 days. Measurement of resting arterial pH, P(CO2) and plasma bicarbonate showed a non-respiratory acidosis immediately after birth which was corrected in the first 24-28 hr: thereafter, the acid-base pattern was of a compensated respiratory alkalosis.2. When CO(2) was added to the inspired gases and resting arterial oxygen tension (P(a), (O2)) was controlled, the average increase in minute ventilation (V) was 0.075 l.min(-1).kg(-1).mm Hg, P(a), (CO2) (-1) and duplicate responses in the same lamb differed by 6-22.5%.3. The slope of the V/P(a), (CO2) line (S) varied inversely with P(a), (O2). In one lamb, severe hypoxia (P(a), (O2) = 21 mm Hg) caused a marked depression of the slope.4. Neither the slope S nor the horizontal intercept B of the lines was related to the age of the lamb. B was not related to pH(a) and only slightly affected by acute hypoxia. B was related to arterial [HCO(3) (-)] and values for both were reduced with the acid-base disturbances seen in the first 10 days after birth. Evidence was given which suggested that the response of the new-born lamb to inhaled CO(2) was similar to that of man acclimatized to a P(a), (O2) of 70-75 mm Hg.5. In the lightly anaesthetized lamb, bilateral section of the sinus nerves caused a small reduction in the sensitivity to inhaled 5% CO(2) in air, an increase in the respiratory lag and a reduction in the rate at which V increased.6. It was concluded that, in the new-born lamb, the carotid chemo-receptors are involved in the response to inhaled CO(2) and that hypoxia potentiates this response.
M J Purves
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of physiology     Volume:  185     ISSN:  0022-3751     ISO Abbreviation:  J. Physiol. (Lond.)     Publication Date:  1966 Jul 
Date Detail:
Created Date:  1967-07-30     Completed Date:  1967-07-30     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  0266262     Medline TA:  J Physiol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  78-94     Citation Subset:  IM    
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MeSH Terms
Acidosis / etiology
Animals, Newborn / physiology*
Anoxia / physiopathology*
Bicarbonates / blood
Blood Gas Analysis
Carbon Dioxide / pharmacology*
Carotid Body / physiology*
Hydrogen-Ion Concentration
Respiration / physiology*
Reg. No./Substance:
0/Bicarbonates; 124-38-9/Carbon Dioxide

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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