Low Body Weight and Cardiac
Tolerance to Ischemia
in Neonatal Rats
Z. CHVOJKOVÁ, I. OŠŤÁDALOVÁ, B. OŠŤÁDAL
Center for Experimental Cardiovascular Research, Institute of
Physiology, Academy of Sciences of the Czech Republic, Prague,
Czech Republic
Received July 14, 2004
Accepted October 19, 2004
On-line available December 9, 2004
Summary
Adaptation to intermittent high altitude hypoxia (IHAH)
increases tolerance of the isolated neonatal rat heart to
ischemia and potentiates protection induced by ischemic
preconditioning. In addition to the protective effect, IHAH
significantly reduces growth of the animals. The aim of the
present study was, therefore, to find out whether low body
weight per se might influence cardiac sensitivity to oxygen
deprivation. Low body weight was induced either by IHAH
(barochamber, 8 h/day, 5000 m) from postnatal day 1 to 10
(HLBW), or by a higher number of sucklings per mother (14
instead of 8), again from postnatal day 1 to 10 (NLBW). Control
animals (8 littermates per mother) were kept under normoxic
conditions (Controls). The recovery of developed force following
40 min of global ischemia was measured in isolated hearts from
10-day-old rats by perfusing them in the Langendorff mode with
Krebs-Henseleit solution at constant pressure, temperature and
rate. Ischemic preconditioning was induced by three 3-min
periods of global ischemia, each separated by 5-min periods of
reperfusion. Low body weight in HLBW and NLBW groups was
accompanied by increased hematocrit, and decrease in absolute
heart weight (both wet and dry) and developed force. On the
other hand, higher hydration, increased cardiac tolerance to
ischemia and potentiation of protection by ischemic
preconditioning were observed in HLBW rats only. This
experimental group also exhibited the highest relative heart
weight. It may be concluded that low body weight alone does not
influence cardiac tolerance to ischemia in neonatal rats.
Key words
High altitude hypoxia • Low body weight • Cardiac tolerance to
ischemia • Neonatal rats
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