Document Detail

Myoglobin-enhanced oxygen delivery to isolated cardiac mitochondria.
MedLine Citation:
PMID:  17562881     Owner:  NLM     Status:  MEDLINE    
The heart, red skeletal muscles and the nitrogen-fixing legume root nodule function in steady states of high oxygen influx, partial oxygenation of cytoplasmic myoglobin or leghemoglobin and correspondingly low oxygen partial pressure. Here, we ask: what conditions are required at the surface of actively respiring, state III, tightly coupled mitochondria to enhance oxygen flow to cytochrome oxidase? Pigeon heart mitochondria were isolated with minimal damage to the outer mitochondrial membrane and were incubated at low oxygen pressures, where respiration is oxygen limited, with solutions of each of six monomeric hemoglobins with widely divergent kinetics and equilibria in their reactions with oxygen: Busycon myoglobin, horse myoglobin, Lucina hemoglobins I and II, soybean leghemoglobin c and Gasterophilus hemoglobin. Each augments oxygen uptake. The declining fractional saturation of each hemoglobin with oxygen was monitored spectrophotometrically as mitochondrial respiration depleted the oxygen; the oxygen partial pressure at half-maximal rate of oxygen uptake was similar for each hemoglobin, supporting the conclusion that the hemoglobins did not interact with the mitochondrial surface in oxygen delivery. The oxygen pressure required to support state III mitochondrial oxygen uptake, 0.005 kPa (0.04 torr), is small compared with that obtained in the sarcoplasm and at the mitochondrial surface of the working heart, 0.32 kPa (2.4 torr). We conclude that, in normal steady states of contraction of the myoglobin-containing heart, oxygen utilization by mitochondrial cytochrome oxidase is not limited by oxygen availability.
Jonathan B Wittenberg; Beatrice A Wittenberg
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  The Journal of experimental biology     Volume:  210     ISSN:  0022-0949     ISO Abbreviation:  J. Exp. Biol.     Publication Date:  2007 Jun 
Date Detail:
Created Date:  2007-06-12     Completed Date:  2007-08-30     Revised Date:  2007-12-03    
Medline Journal Info:
Nlm Unique ID:  0243705     Medline TA:  J Exp Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  2082-90     Citation Subset:  IM    
Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
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MeSH Terms
Columbidae / metabolism
Hemoglobins / metabolism
Mitochondria, Heart / metabolism*
Myoglobin / metabolism*
Oxygen / metabolism*
Oxygen Consumption
Reproducibility of Results
Spectrophotometry / methods
Grant Support
1K6-733//PHS HHS
Reg. No./Substance:
0/Hemoglobins; 0/Myoglobin; 7782-44-7/Oxygen

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