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Effects of thyroid state on respiration of perfused rat and guinea pig hearts
Ist Teil von
American journal of physiology. Heart and circulatory physiology, 1987-09, Vol.253 (3), p.H519-H523
Ort / Verlag
United States
Erscheinungsjahr
1987
Quelle
MEDLINE
Beschreibungen/Notizen
L. C. Read, P. G. Wallace and M. N. Berry
The effects of thyroid state on the respiration of the isolated heart were
investigated using retrograde perfused rat and guinea pig hearts. In both
species, hypothyroidism caused a marked depression in circulating thyroid
hormone concentrations and in the respiration of the isolated, retrograde
perfused heart. The effects on myocardial respiration could be attributed
to changes in the contraction frequency and in the oxygen consumption per
beat, with little contribution from basal respiration. Treatment of animals
with thyroxine elevated plasma thyroid hormones to a similar extent in rats
and guinea pigs. In the latter, thyroxine treatment was associated with
substantial increases in the contraction frequency and the oxygen
consumption per beat of the isolated heart. In contrast, only small changes
were apparent in the retrograde perfused rat heart, observations that were
confirmed in rat hearts perfused at near physiological work loads. It was
concluded that rat hearts isolated from normal animals function at near
maximal thyroid state, in contrast to the guinea pig heart, which requires
higher circulating concentrations of thyroid hormones to attain maximal
responses.