European Journal of Cardio-Thoracic Surgery, Vol 4, 492-497, Copyright © 1990 by European Association for Cardio-thoracic Surgery
Age-dependent changes in the tolerance of the rabbit heart to ischemia
T Murashita, RD Kempsford and DJ Hearse
Rayne Institute, St. Thomas Hospital, London, UK.
Many studies in several species have demonstrated an enhanced ischemic
tolerance in the immature myocardium when compared with the adult. Little
is known about the rate at which these changes occur. We have compared the
extent of post-ischemic recovery using isolated working hearts from rabbits
of various ages (7-90 days). Hearts (n = 8/group) from rabbits of 7, 14,
21, 28, 31, 40 and 60-90 days of age were perfused aerobically (37 degrees
C) for 20 min and control indices of cardiac function were recorded. The
hearts were then arrested (2 min infusion) with the St. Thomas' Hospital
cardioplegic solution and subjected to global ischemia for 45 min (37
degrees C). The hearts were then reperfused for 15 min in the Langendorff
mode and 20 min in the working mode. Leakage of creatine kinase (CK) during
Langendorff reperfusion and the recovery of cardiac function during working
perfusion were measured. Pre-ischemic cardiac output (CO) was 58.6 +/- 2.6,
80.1 +/- 2.9, 117.5 +/- 4.5, 131.9 +/- 3.2, 134.1 +/- 2.1, 152.0 +/- 1.6
and 165.8 +/- 4.6 ml/min in the 7, 14, 21, 28, 31, 40 and 60-90 day-old
groups, respectively. Following ischemia, CO recovered to 82.9 +/- 3.6,
79.2 +/- 3.1, 77.9 +/- 3.4, 72.3 +/- 2.7, 55.3 +/- 2.1, 35.7 +/- 2.9 and
33.1 +/- 6.9%, respectively. CK leakage correlated poorly with recovery and
was 31.5 +/- 4.7, 32.0 +/- 8.5, 33.6 +/- 7.9, 35.8 +/- 7.0, 37.3 +/- 4.4,
38.7 +/- 4.8 and 30.4 +/- 5.9 IU/15 min per gram dry weight,
respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
