Downward-shift of coronary pressure-flow relationship following a
brief period of ischemia in dogs.
Morioka, Toshikazu, Masafumi Kitakaze, Tetsuo Minamino, Seiji
Takashima, Koichi Node, Yasushi Okazaki, Hiroshi Sato, Yoshiro
Shinozaki, Mitsuaki Chujo, Hidezo Mori, Koji Miyazaki, Michitoshi
Inoue, Masatsugu Hori, Takenobu Kamada.
The First Department of Medicine, Osaka University School of
Medicine, Osaka Tokai University School of Medicine, Department of
Physiology II, Isehara Keio University School of Medicine,
Cardiopulmonary Division, Tokyo, Department of Information Science,
Osaka University Hospital, Osaka, Japan
APStracts 2:0192H, 1995.
This study was undertaken to test whether a brief period of ischemia
affects the coronary pressure-flow relationship during reduction of
coronary perfusion pressure (CPP). The left anterior descending
coronary artery was cannulated and perfused with blood from the left
carotid artery in 40 open-chest dogs. Coronary blood flow (CBF) was
measured during intracoronary administrations of papaverine and
adenosine. The coronary pressure-flow relationship was assessed
during transient reduction of CPP from 100 to 30 mmHg. Coronary
hyperemic flow due to adenosine and papaverine was attenuated 30 min
after transient 10 and 15 min of ischemia. In the group of transient
10 min ischemia, both fractional shortening (FS) and CBF returned to
the pre-ischemic values at 30 and 60 min of reperfusion, however,
marked decreases in CBF (35+5 vs 56+4 ml/100g/min at CPP=60 mmHg,
p<0.01) during graded reductions in CPP were observed. The
endomyocardial blood flow was reduced relative to the control
condition. Furthermore, both FS (6+1 vs 14+1 % at CPP=60 mmHg,
p<0.01) and lactate extraction ratio (-41+15 vs 1+6 % at CPP=60
mmHg, p<0.05) were decreased. The downward-shift of the coronary
perfusion pressure-flow relationship and the deterioration of
myocardial contractile and metabolic function during reduction of CPP
were restored 60 min after the onset of reperfusion. In contrast, in
the group of transient 15 min ischemia, although both baseline FS and
coronary hyperemic flow due to adenosine and papaverine remained to
be reduced 30 and 60 min after the onset of reperfusion, the coronary
perfusion pressure-flow relationship was not shifted. These results
indicate that a transient brief period of ischemia can reversibly
affect the coronary pressure-flow relationship due to the reduced
capability of vascular relaxation, however, the downward-shift of
coronary pressure-flow relationship can be blunted when the
myocardial contractile dysfunction due to transient ischemia becomes
apparent.
Received 18 July 1994; accepted in final form 26 April 1995.
APS Manuscript Number H626-4.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 9 May 1995.