Regional myocardial heat-shock protein (HSP70) concentrations under different blood flow conditions |
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| Authors: | Robert Loncar Christian W Flesche A Deussen |
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| Institution: | Institut für Physiologie, Medizinische Fakult?t Carl Gustav Carus der TU Dresden, Fetscherstr. 74, D-01307 Dresden, Germany, DE
Institut für Klinische An?sthesiologie, Heinrich-Heine-Universit?t Düsseldorf, Germany, DE
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| Abstract: | The concentration of heat-shock proteins of 70 kD (HSP70) in heart tissue has been shown to increase during transient myocardial
ischaemia and to persist during several hours of reperfusion. In this study the relationship between the local myocardial
HSP70 concentration and blood flow was addressed for control physiological conditions and acute myocardial ischaemia. A specific
aim of this study was to address the question of whether low flow areas under control physiological conditions have undergone
a transient ischaemia during the preceding hours and thus may be in a state of hibernation or stunning. In 12 anaesthetized,
open-chest beagle dogs (6 control and 6 with 60-min coronary artery stenosis) heart rate, mean aortic pressure, mean arterial
partial pressure of O2 and partial pressure of CO2 averaged 85±16 beats/min, 94±14 mmHg, 102±17 mmHg and 39±6 mmHg, respectively. Regional HSP70 and myocardial blood flow (RMBF)
were measured using an HSP70-enzyme-linked immunosorbent assay and the tracer microsphere technique, respectively, in samples
of 250 mg wet mass. In the control group the mean RMBF was 1.06±0.59 ml·min–1·g–1 and the local HSP70 concentration was 7.08±1.03 μg/mg cytosolic protein. Myocardial HSP70 showed a blood flow-independent
regional biological heterogeneity, equivalent to a coefficient of variation of 0.31. Local HSP70 concentrations did not differ
(P>0.05) between control low and high flow samples, 6.16±1.0 vs 6.08±0.75 μg/mg cytosolic protein, respectively. However, after
60 min of coronary artery occlusion the local HSP70 concentration increased from 7.08 ±1.03 to 13.43±3.19 μg/mg cytosolic
protein (P<0.001). There was a significant inverse relationship between the percent reduction of local blood flow and HSP70 (r=–0.56, P<0.001). From these results it is concluded that: (1) low flow samples under control physiological conditions are unlikely
to be in a state of hibernation or stunning since their HSP70 concentration is normal and (2) the increase in the local HSP70
concentration during myocardial ischaemia reflects the degree of impairment of O2 delivery.
Received: 29 May 1998 / Received after revision: 14 August 1998 / Accepted: 25 August 1998 |
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| Keywords: | Flow heterogeneity Hibernation Metabolic markers of ischaemia Stunning |
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