Differences in myocardial stunning following coronary artery
occlusion in conscious dogs, pigs and baboons.
Shen, You-Tang, and Stephen F. Vatner.
Departments of Medicine, Harvard Medical School, Brigham &
Women's Hospital, Boston, MA 02115 and the New England Regional
Primate Research Center, Southborough, MA 01772
APStracts 2:0406H, 1995.
To determine whether myocardial stunning differs among dogs, pigs and
baboons, and is reproducible within species, we examined 9 conscious
dogs, 12 minipigs, and 6 baboons chronically instrumented with a left
circumflex coronary occluder, dimension crystals, left ventricular
pressure gauge and aortic and left atrial catheters. During 10 min
coronary artery (CA) occlusion (O), systolic wall thickening in the
ischemic zone fell similarly in dogs (-108+/-5.6%), pigs (-102+/
-1.8%) and baboons (-107+/-5.7%), but blood flow fell more,
p<0.05, in the subepicardium in pigs (0.07+/-0.01 ml/min/g) and
baboons (0.07+/-0.02 ml/min/g) than in dogs (0.18+/-0.03 ml/min/g).
At 1 hr after CA reperfusion (R), wall thickening was reduced more
(p<0.05) in dogs (-40+/-4.2%) than pigs (-22+/-2.1%) and baboons
(-4+/-2.4%). wall thickening returned to baseline levels later (68+/
-9 min) during CAR in baboons, pigs (4.3+/-0.5 hr), and in dogs
(12.0+/-2.4 hr). In 5 dogs and 5 pigs, 3 separate 10 min CAO, each 2
days apart, were also examined. In dogs, effects during CAO were
similar but reductions in wall thickening after CAR were
significantly less following the second (-26+/-4.2%) or third (-30+/
-3.2%) CAO, compared to the first CAO (-47+/-4.9%). In contrast,
repetitive CAO did not induce differences in recovery of wall
thickening in pigs. In 4 dogs where increases in myocardial
metabolism were minimized by pretreatment with ganglionic and
-adrenergic receptor blockades, depression of wall thickening at 1 hr
CAR was similar (-52+/-12.2%) to that observed in dogs when heart
rate rose in the intact state. Furthermore, the recovery of wall
thickening following CAR was also improved after the third as
compared with the first CAO. These results indicate that myocardial
stunning is less severe in conscious pigs and baboons, as compared
with conscious dogs, despite more intense transmural ischemia. The
conscious dogs demonstrated a "preconditioning-like effect",
with serial brief CAO, which was not exhibited in conscious pigs.
Received 21 March 1995; accepted in final form 24 August 1995.
APS Manuscript Number H272-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 23 September 1995.