AJP - Heart and Circulatory Physiology, Vol 243, Issue 6 1027-H1031, Copyright © 1982 by American Physiological Society
Myocardial pH during regional ischemia: evaluation of a fiber-optic photometric probe
G. A. Tait, R. B. Young, G. J. Wilson, D. J. Steward and D. C. MacGregor
The relationship between the decrease in intramyocardial extracellular pH
and the degree of stenosis of the left anterior descending (LAD) coronary
artery was studied in eight dogs pretreated with propranolol.
Intramyocardial pH was measured with a miniature glass pH electrode and
with a new photometric pH probe that uses fiber-optic filaments to measure
the color change of an indicator substance in a small permeable chamber.
The LAD was cannulated and perfused from the axillary artery. Cannula flow
was measured with an electromagnetic flow probe, and regional myocardial
blood flow (RMBF) was measured with radioactive microspheres before and at
the end of a period of critical stenosis, 2/3 reduction of flow, or total
occlusion of the LAD cannula. In the region of the glass electrode, the
mean RMBF (+/-SE) decreased by 16.3 +/- 3.3, 52.7 +/- 7.3, and 84.8 +/-
6.5% during the three levels of stenosis, and the pH correspondingly
decreased by 0.05 +/- 0.01, 0.29 +/- 0.10, and 0.94 +/- 0.17 units. In the
region of the photometric probe, the RMBF decreased 19.1 +/- 1.3, 47.2 +/-
6.7, and 84.3 +/- 6.0%, and the pH decreased by 0.05 +/- 0.02, 0.14 +/-
0.04, and 0.76 +/- 0.18 units. There was no statistically significant
difference between the two types of pH sensor.
