HEAT-SHOCK PROTEIN-CHANGES IN HIBERNATION - A SIMILARITY WITH HEART-FAILURE

Myocardial hibernation is an adaptive phenomenon occurring during isch aemia, Patients with hibernating myocardium often have a history of an acute ischaemic insult, followed by prolonged hypoperfusion and sympt oms of congestive heart failure (CHF), which is a complex syndrome inv olving several adaptational mechanisms. Mie tested the hypothesis that these two conditions evoke the myocardial expression of heat shock pr otein 72 (hsp72) as an adaptive response at the molecular level. Short -term acute hibernation was induced in isolated and perfused rat heart s subjected to 8 min total ischaemia followed by 292 min low-flow isch aemia (coronary flow: 1.0 ml/min), followed by 60 min of reperfusion. Total ischaemia caused quiescience, Subsequent low-flow resulted in a temporal early increase of lactate release, no re-establishment of dev eloped pressure, no increase in diastolic pressure. Reperfusion result ed in 85.7 +/- 7.2% recovery of developed pressure, a small washout of lactate and CPI(, no contracture, confirming that viability was maint ained despite prolonged hypoperfusion. This sequence of events was lin ked to an increase in hsp72 content in the right (from 18.1 +/- 3.8% t o 34.6 +/- 2.3%, P<0.01) and left (from 19.7 +/- 2.6% to 37.6 +/- 3.3% , P<0.01) ventricles, Three-hundred min of low-flow perfusion of the r at heart in absence of the short period of total ischaemia caused irre versible damage and failed to induced hsp72. CHF was induced in rats b y intraperitoneal administration of monocrotaline. As a result, right Ventricular weight increased from 171.3 +/- 7.2 to 412.3 +/- 18.7 mg, P<0.001, peripheral and pleural effusion were evident and measurable, plasma arterial natriuretic peptide increased from 15.2 +/- 1.9 to 123 .5 +/- 5.4 pg/mI, P<0.001, confirming the occurrence of the syndrome o f CHF, This was concomitant with significant expression of hsp72, more evident in the right (from 5.0 +/- 0.9% to 39.4 +/- 1.6%, P<0.001) th an in the left (from 3.5 +/- 0.6% to 13.0 +/- 1.2%, P<0.001) ventricle . These data suggest that an adaptational process occurs at myocardial level during either hibernation or CHF. The expression of hsp72 could be viewed as a stereotyped adaptational reaction of the cardiac cell to stress conditions. (C) 1996 Academic Press Limited