Vol. 86, Issue 3, 832-839, March 1999
Lactate kinetics at rest and during exercise in lambs with
aortopulmonary shunts
Gertie C. M.
Beaufort-Krol1,
Willem G.
Zijlstra1,
Janny
Takens1,
Marieke C.
Molenkamp1,
Koos J.
Meuzelaar2,
Gioia B.
Smid1, and
Jaap R. G.
Kuipers1
1 Division of Pediatric
Cardiology, Beatrix Children's Hospital, and
2 Department of Thoracic
Surgery, University of Groningen, and Groningen-Utrecht Institute
for Drug Exploration, 9700 RB Groningen, The Netherlands
In a previous
study [G. C. M. Beaufort-Krol, J. Takens, M. C. Molenkamp, G. B. Smid, J. J. Meuzelaar, W. G. Zijlstra, and J. R. G. Kuipers.
Am. J. Physiol. 275 (Heart Circ. Physiol. 44): H1503-H1512, 1998], a lower systemic
O2 supply was found in lambs with
aortopulmonary left-to-right shunts. To determine whether the lower systemic O2 supply
results in increased anaerobic metabolism, we used
[1-13C]lactate to
investigate lactate kinetics in eight 7-wk-old lambs with shunts and
eight control lambs, at rest and during moderate exercise
[treadmill; 50% of peak O2
consumption (
O2)].
The mean left-to-right shunt fraction in the shunt lambs was 55 ± 3% of pulmonary blood flow. Arterial lactate concentrations and the rate of appearance (Ra) and
disappearance (Rd) of lactate
were similar in shunt and control lambs, both at rest (lactate: 1,201 ± 76 vs. 1,214 ± 151 µmol/l;
Ra = Rd: 12.97 ± 1.71 vs. 12.55 ± 1.25 µmol · min
1 · kg1)
and during a similar relative workload. We found a positive correlation
between Ra and systemic blood
flow, O2 supply, and O2 in both groups of lambs.
In conclusion, shunt lambs have similar lactate kinetics as do control
lambs, both at rest and during moderate exercise at a similar fraction
of their peak O2, despite a
lower systemic O2 supply.
congenital heart disease; lactate turnover rate; carbon-13-labeled
substrates; metabolism; peak oxygen consumption
