R. Southworth et al., DEVELOPMENTAL DIFFERENCES IN SUPEROXIDE PRODUCTION IN ISOLATED GUINEA-PIG HEARTS DURING REPERFUSION, Journal of Molecular and Cellular Cardiology, 30(7), 1998, pp. 1391-1399
The production of free radicals on reperfusion has been implicated as
an important factor governing post-ischemic recovery of cardiac functi
on. Although the response of the heart to ischemia and reperfusion is
known to change during cardiac development, it is not known if differe
nt rates of free radical production play a role in these altered respo
nses. The aim of this investigation was to determine if the production
of the superoxide anion (O-2(-)) on reperfusion differs in the immatu
re and mature heart. Immature hearts, obtained from 3-day premature gu
inea pigs (delivered by cesarean section) were compared with those fro
m adults (7 weeks old), Using the isolated Langendorff preparation. O-
2(-) production was measured during reperfusion following ischemic dur
ations [0 (aerobic control), 15, 20, 30, and 60 min, n=6/group] by the
reduction of succinylated ferricytochrome c in the perfusate, Both im
mature and mature hearts exhibited a bell-shaped relationship between
ischemic duration and peak O-2(-) production on reperfusion: (13.4 +/-
5.9: 22.2 +/- 5.4; 23.0 +/- 7.8; 59.3 +/- 16.2; 33.7 +/- 15.1, 32.6 /- 8.5 nmol/min/g wet weight in the immature heart and 15.7 +/- 1.9; 5
5.0 +/- 30.2; 82.8 +/- 14.0; 78.8 +/- 33.8; 40.6 +/- 16.4; 45.4 +/- 13
.1 nmolmin/g wet weight in the mature heart after 0; 15; 20; 30; 45 an
d 60 min of ischemia, respectively), A similar relationship was also d
emonstrated with total O-2(-) production over the 20-min reperfusion p
eriod: (134.0 +/- 57.1: 106.5 +/- 46.2: 199.3 +/- 50.6; 362.0 +/- 99.5
; 375.0 +/- 60.9; 221.0 +/- 73.0 nmol/20 min/g wet weight in the immat
ure heart and 97.8 +/- 54; 282.0 +/- 139.0; 933.3 +/- 210.3; 964.0 +/-
374.0; 443.0 +/- 106.0; 352.0 +/- 1551.0 nmol/20 min/g wet weight in
the mature heart after 0, 15, 20, 30, 45 and 60 min of ischemia, respe
ctively). Mature hearts consistently produced more O-2(-) than immatur
e hearts on reperfusion, while there was no significant difference in
their capacity to produce O-2(-) during aerobic perfusion, We conclude
that the immature heart may be at less risk from the free radical com
ponent of reperfusion injury than the mature heart. (C) 1998 Academic
Press.