Heterogeneity of local myocardial flow and oxidative metabolism.
In mammalian hearts, local myocardial flow (LMF) varies between 20 and 200% of the mean. It is not clear whether oxidative metabolism has a similar degree of heterogeneity. Therefore, we investigated the relation between LMF and local oxidative metabolism in isolated rabbit hearts. Buffer oxygenation with (18)O(2) resulted in labeled myocardial oxidation water (H(2)(18)O). In four hearts, myocardial oxygen consumption (MVO(2)) was calculated from the H(2)(18)O production and compared with that calculated according to Fick. In eight additional hearts, LMF was measured using microspheres. Coronary venous H(2)(18)O kinetics and local H(2)(18)O residues were determined and analyzed by mathematical modeling. MVO(2) recovery from H(2)(18)O was >93% compared with that according to Fick. LMF ranged from 1.91 to 11.24 ml. min(-1). g(-1), and local H(2)(18)O residue ranged from 0.41 to 1.04 micromol/g. Both variables correlated (r = 0.62, n = 64, P < 0.001). Measurements in nine hearts were fitted by modeling using capillary permeability-surface area products (PS(c)) from 2 to 10 ml. min(-1). g(-1). With flow-proportional PS(c), a 3.33-fold difference in LMF was associated with a 6.45-fold difference in local MVO(2). Both LMF and local oxidative metabolism are spatially heterogeneous, and they correlate to one another.
Schwanke
U
U
Department of Pathophysiology, University of Essen Medical School, D-45122 Essen, Germany.
Deussen
A
A
Heusch
G
G
Schipke
J D
JD
D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology; D001834:Body Water / Q000737:chemistry / Q000378:metabolism; D002138:Calibration; D002199:Capillary Permeability / Q000502:physiology; D003326:Coronary Circulation / Q000502:physiology*; D066298:In Vitro Techniques; D016014:Linear Models; D008863:Microspheres; D008954:Models, Biological; D009206:Myocardium / Q000378:metabolism*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D010101:Oxygen Consumption / Q000502:physiology; D010103:Oxygen Isotopes; D011817:Rabbits
D010103:Oxygen Isotopes; D010100:Oxygen