AJP - Heart and Circulatory Physiology, Vol 261, Issue 3 768-H773, Copyright © 1991 by American Physiological Society
Effects of coronary occlusion duration on reactive hyperemia in conscious dogs and ponies
R. D. Sarazan, G. F. Krause, D. Franklin, H. E. Garner and D. M. Griggs Jr
John M. Dalton Research Center, Department of Statistics, University of Missouri, Columbia 65211.
Coronary reactive hyperemia duration (RHD) and coronary blood flow debt
repayment (BFDR) were compared in conscious dogs and ponies instrumented
with coronary artery Doppler flow probes and pneumatic occluders.
Additional ponies were instrumented with pacing electrodes. With the use of
a Latin square design, eight animals of each species were subjected to a
randomized series of nine coronary occlusions ranging from 5 s to 2 min in
duration. In both species, postocclusion blood flow velocity rose rapidly
and plateaued at similar peak levels relative to control, but in ponies
this plateau lasted significantly longer. The interspecies difference in
plateau duration increased as a function of coronary occlusion duration
(COD). RHD ranged from 19.5 +/- 5.9 to 139.7 +/- 5.9 s in dogs and from
26.6 +/- 9.0 to 395.0 +/- 9.0 s in ponies. The slope of the RHD vs. COD
curve was steeper in ponies. BFDR was similar in dogs and ponies at the
shortest COD (418.1 +/- 26 vs. 451.4 +/- 58%) but declined in dogs as a
function of COD to 232.3 +/- 26%. In ponies, BFDR increased as a function
of COD to a maximum of 945.4 +/- 58% with a 60-s occlusion and then
declined to 614.3 +/- 58%. RHD was not significantly altered in ponies when
heart rate was changed to match that in dogs. Although the underlying basis
for these interspecies differences in RHD and BFDR was not determined, the
differences were considered to be too large to be explained by animal model
differences in coronary conductance, collateral blood flow, or myocardial
oxygen consumption.(ABSTRACT TRUNCATED AT 250 WORDS)
