Quantitative determination of regional oxygen consumption in the dog heart.

Abstract

ENERGY COSTS vary with an organ's functional needs. The same relationship applies within different regions of the same organ. In vivo regional differences in O t consumption are known within some organs, e.g., white and gray matter of the cerebral cortex, subepicardium, and subendocardium of the left ventricle, and cortex and medulla of the kidney. "3 Only qualitative evidence for these differences exist. We have developed a technique that can quantitatively measure these differences in regional O 2 consumption under different functional conditions. Regional Oj extraction is measured, using our recently developed microspectrophotometric technique, 4 -B and regional blood flow is determined with radioactive microspheres. Regional O 2 consumption is calculated from these data by the Fick principle.This method of determination of regional O, consumption has been applied to the heart where there are clear differences in cardiac work between the right, left, and septal ventricular walls. Until now, there has been no way to quantitate this difference in terms of O 2 consumption. Differences in blood flow have been reported between the ventricular walls, 6 ' 7 but no disparity has been found between the average arteriovenous O t difference of the right, septal, and left ventricular walls, although within the left ventricular wall some regional arteriovenous O s saturation differences exist. 8 We have studied O t extraction and flow in the same dog and determined differences in O t consumption between the ventricular walls.In the left ventricular free wall, there has been some qualitative evidence for regional differences in O 2 consumption as a function of depth within the wall. The

Evaluation of transmural distribution of viable muscle by myocardial strain profile and dobutamine stress echocardiography

“…The left ventricular myocardium demonstrates transmural heterogeneity of strain distribution. It has been reported that, under normal circumstances, the subendocardial myocardium receives more blood flow and consumes more oxygen than the subepicardial one (20,28,35). Moreover, there is a transmural gradient of contractile function in the left ventricular wall, with greatest amount of thickening occurring in the subendocardial myocardium (6,25).…”

Role of Propranolol in Improvement of the Relationship between O2 Supply and Consumption in an Ischemic Region of the Dog Heart

“…The accuracy and limitations of the method used to determine regional 02 consumption has been described in detail previously (22)(23)(24). Briefly, the accuracy of our determination of 02 consumption depends on the accuracy of the determination of arterial and venous 02 content and blood flow as well as the limitations of the Fick principle itself.…”

“…Samples were prepared for analysis of regional microsphere distribution and for microspectrophotometric analysis as described (24). Briefly, 30 um-thick frozen tissue sections were cut on a cold rotary microtome in a -25°C cold box in an N2 atmosphere.…”

“…Microspectrophotometric observations of small regional arteries and veins in quick-frozen hearts were made to determine regional 02 extraction and were combined with regional measurements of blood flow with radioactive microspheres to determine regional myocardial 02 consumption and the 02 supply/consumption ratio (21)(22)(23)(24).…”

The mechanical and metabolic basis of myocardial blood flow heterogeneity

“…After polishing the cut surfaces of quick-frozen pieces of myocardium, Weiss et al (102) measured spectrophotometrically the hemoglobin saturation with oxygen in small arteries and veins, and demonstrated that more oxygen was used in high-flow regions than in low-flow regions. Caldwell et al (27) observed that the local capacity for the uptake of fatty acid was proportional to the regional flows in the hearts of dogs running on the treadmill.…”