Journal of Applied Physiology, Vol 57, Issue 2 551-561, Copyright © 1984 by American Physiological Society
Coronary transport reserve in normal dogs
M. H. Laughlin
This study was designed to determine an acceptable method for producing
maximal coronary vasodilation for quantifying coronary blood flow reserve
and coronary capillary transport reserve. The anterior descending branch of
the left coronary artery was cannulated and pump-perfused while aortic,
central venous, and coronary perfusion pressures, heart rate,
electrocardiogram, blood gases, and coronary blood flow (CBF) were
continuously monitored. All parameters were measured at four to six points
along the coronary pressure-flow autoregulation curve. Myocardial
extraction and permeability-surface area products (PS) of
51Cr-ethylenediaminetetraacetic acid were determined with the
single-injection indicator-diffusion method in intact working hearts of
anesthetized dogs. Maximal vasodilations were produced with 2-min coronary
occlusions and with intracoronary infusions of adenosine (ADO),
dipyridamole, ADO + dipyridamole, papaverine, and ADO + alpha 1-receptor
blockade. ADO was chosen to quantify coronary transport reserve because it
produced maximal CBF's and PS's that were reproducible within and among
animals and produced minimal effects on the cardiovascular system. Under
base-line conditions, there was no relationship between PS and perfusion
pressure. Base-line PS averaged 20 +/- 2 ml X min-1 X 100 g-1. Maximal
vasodilation with constant CBF had no significant effect on PS. During
maximal vasodilation, CBF and PS increased linearly with increasing
perfusion pressure, and PS increased linearly with increasing plasma flow.
Constant pressure maximal vasodilation with ADO caused PS to increase to 36
+/- 4 ml X min-1 X 100 g-1, and CBF was increased 380%.
