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ABSTRACT Previous studies show that mitochondria adapt to changes of arterial PO2. The present study investigates heart and brain mitochondrial respiratory rate (RR) in 23 guinea pigs at

varying blood COHb levels. Blood gases and [COHb] were recorded in all animals. Brain and heart mitochondria were isolated. State 4 RR, state 3 RR with glutamate-malate substrate, expressed

as nm O2/min/nm cytochrome a+a3, respiratory control ratio(RCR) (state 3/state 4), and Ca++ uptake were measured. All preparations were well coupled with RCR 10.7±1.9 for heart and 8.3±1.2

for brain mitochondria. State 3 RR increased from 225 at 0% COHb to 500 at 40% COHb in the heart (r=.8) and from 260 at 0% COHb to 628 at 80% COHb in the brain (r=.7). There was an inverse

correlation of state 3 RR and arterial O2 content. Mitochondrial activity increased from 190-525 as arterial O2 content decreased from 19-9 ml/dl (r=.9) and from 340 to 580 as arterial O2

content decreased from 16-4 ml/dl (r=.6) in heart and brain respectively. Ca++ uptake in heart and brain increased with increasing [COHb]. Blood flow was not measured but presumably

circulatory adjustment failed to compensate for the decreased arterial O2 content, thus impairing O2 delivery to the tissues. These data suggest that increased mitochondrial activity with

increased [COHb] and decreased O2 content, occurring in the presence of normal PaO2, represent an adaptive response to tissue hypoxia comparable to the changes reported during acute and

chronic hypoxemia. ARTICLE PDF AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * Department of Pediatrics, University of Pennsylvania, Philadelphia, PA. Linda M Sacks, David Herbert, Crosby

Roper, Thomas Heffernan & Maria Delivoria-Papadopoulos Authors * Linda M Sacks View author publications You can also search for this author inPubMed Google Scholar * David Herbert View

author publications You can also search for this author inPubMed Google Scholar * Crosby Roper View author publications You can also search for this author inPubMed Google Scholar * Thomas

Heffernan View author publications You can also search for this author inPubMed Google Scholar * Maria Delivoria-Papadopoulos View author publications You can also search for this author

inPubMed Google Scholar RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Sacks, L., Herbert, D., Roper, C. _et al._ 1717 MITOCHONDRIAL RESPIRATORY

ACTIVITY: RESPONSE TO INCREASED CARBOXYHEMOGLOBIN (COHb) IN BRAIN AND HEART OF GUINEA PIGS. _Pediatr Res_ 15 (Suppl 4), 729 (1981). https://doi.org/10.1203/00006450-198104001-01736 Download

citation * Issue Date: 01 April 1981 * DOI: https://doi.org/10.1203/00006450-198104001-01736 SHARE THIS ARTICLE Anyone you share the following link with will be able to read this content:

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