Thyroid hormone and cardiac function in mice deficient in thyroid hormone receptor-alpha or -beta: an echocardiograph study.
We investigated the effect of thyroid hormone (TH) receptor (TR)alpha and -beta isoforms in TH action in the heart. Noninvasive echocardiographic measurements were made in mice homozygous for disruption of TRalpha (TRalpha(0/0)) or TRbeta (TRbeta(-/-)). Mice were studied at baseline, 4 wk after TH deprivation (using a low-iodine diet containing propylthiouracil), and after 4-wk treatment with TH. Baseline heart rates (HR) were similar in wild-type (WT) and TRalpha(0/0) mice but were greater in TRbeta(-/-) mice. With TH deprivation, HR decreased 49% in WT and 37% in TRbeta(-/-) mice and decreased only 5% in TRalpha(0/0) mice from baseline, whereas HR increased in all genotypes with TH treatment. Cardiac output (CO) and cardiac index (CI) in WT mice decreased (-31 and -32%, respectively) with TH deprivation and increased (+69 and +35%, respectively) with TH treatment. The effects of CO and CI were blunted with TH withdrawal in both TRalpha(0/0) (+8 and -2%, respectively) and TRbeta(-/-) mice (-17 and -18%, respectively). Treatment with TH resulted in a 64% increase in LV mass in WT and a 44% increase in TRalpha(0/0) mice but only a 6% increase in TRbeta(-/-) mice (ANOVA P < 0.05). Taken together, these data suggest that TRalpha and TRbeta play different roles in the physiology of TH action on the heart.
Weiss
Roy E
RE
Department of Medicine, University of Chicago, Chicago, Illinois 60637, USA. rweiss@medicine.bsd.uchicago.edu
Korcarz
Claudia
C
Chassande
Olivier
O
Cua
Kevin
K
Sadow
Peter M
PM
Koo
Eugene
E
Samarut
Jacques
J
Lang
Roberto
R
D000818:Animals; D001835:Body Weight; D004452:Echocardiography; D006321:Heart / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout / Q000235:genetics; D011988:Receptors, Thyroid Hormone / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D013960:Thyroid Function Tests; D037042:Thyroid Hormone Receptors beta; D013963:Thyroid Hormones / Q000502:physiology*
D011988:Receptors, Thyroid Hormone; D037042:Thyroid Hormone Receptors beta; D013963:Thyroid Hormones