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AN EXPERIMENTAL APPROACH FOR EVALUATION OF THE O 2 BALANCE IN LOCAL MYOCARDIAL REGIONS IN VIVO
Author(s) -
Kedem Joseph,
Mayevsky Avraham,
Sonn Judith,
Acad Bat-Ami
Publication year - 1981
Publication title -
quarterly journal of experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0144-8757
DOI - 10.1113/expphysiol.1981.sp002591
Subject(s) - oxygen balance , blood flow , contractility , chemistry , cardiology , cardiac output , oxygen , in vivo , medicine , hemodynamics , biology , microbiology and biotechnology , organic chemistry
Quantitative evaluation of myocardial oxygen balance can be accomplished by measurement of oxygen supply, demand, and intracellular oxygen concentration. Experimentally, these parameters are often related to coronary blood flow, cardiac contractility, and mitochondrial NADH redox level, respectively. Methods were developed to measure these three parameters in a local region on the myocardial surface in open‐chest dogs. Local coronary blood supply was measured with the aid of a small surface thermistor, and cardiac work with a miniature strain gauge arch. NADH oxidation‐reduction state was recorded using surface fluorometry through a fibre optic light guide. Transient anoxia produced by nitrogen breathing caused a rapid but reversible elevation in NADH levels, which was not always accompanied by a concomitant change in contractile force. Elevation of heart rate resulted in a rise in intramitochondrial NADH followed by an increase in coronary flow. In spite of the increased flow, NADH levels remained elevated, indicating a change in the O 2 balance; this may indicate that autoregulation does not necessarily result in total compensation.