Hypothyroid dependent myocardial angiotensin receptor trafficking is involved in improved cardiac performance after heat acclimation. 2010

Ronen Durst, and Kobi Goldstein, and Yuval Horowitz, and Aaron Baggish, and Meir Gare, and Yonathan Hasin, and Chaim Lotan, and Michal Horowitz
Cardiology Division, Hadassah Hebrew University Medical Center, Jerusalem, Israel. rdurst@partners.org

OBJECTIVE The renin-angiotensin system (RAS) plays a key role in heat acclimation, a process which induces adaptive changes in cardiac function. These changes are mediated in part by reduced thyroid hormone activity and improve myocardial function during and following exposure to various (non-heat) stresses such as ischemia. The aim of this study was to examine the role of RAS in the development of the heat acclimated protected heart. METHODS Three treatment groups were used: (1) C, controls; (2) AC, heat acclimated rats (1mo 34 degrees C,); and (3) HAEL, heat acclimated euthyroid rats treated with 3ng/ml of eltroxine. A Langendorff perfusion apparatus was used to measure hemodynamic parameters at baseline and following administration of angiotensin-II, losartan and PD123319 in isolated hearts. Protein and mRNA levels of angiotensin receptors were measured. RESULTS Both C and HAEL animals showed increased contractility and a drop in coronary flow during angiotensin II exposure whereas AC animals did not have an inotropic response or vasoconstriction. Significantly different patterns of AT1 and AT2 receptor densities (a 50% reduction and a 30% increase in outer cell membrane AT1 and AT2 receptors respectively) were observed in AC animals compared to the other two groups. AT receptor mRNA levels were similar in all treatment groups. CONCLUSIONS The attenuated response of heat acclimated hearts to angiotensin is mediated by reduced thyroxine levels and is associated with a shift in AT1 receptors from the outer to the inner membrane. This shift appears to be caused by modified posttranslational trafficking of AT receptors.

UI MeSH Term Description Entries
D007037 Hypothyroidism A syndrome that results from abnormally low secretion of THYROID HORMONES from the THYROID GLAND, leading to a decrease in BASAL METABOLIC RATE. In its most severe form, there is accumulation of MUCOPOLYSACCHARIDES in the SKIN and EDEMA, known as MYXEDEMA. It may be primary or secondary due to other pituitary disease, or hypothalamic dysfunction. Central Hypothyroidism,Primary Hypothyroidism,Secondary Hypothyroidism,TSH Deficiency,Thyroid-Stimulating Hormone Deficiency,Central Hypothyroidisms,Deficiency, TSH,Deficiency, Thyroid-Stimulating Hormone,Hormone Deficiency, Thyroid-Stimulating,Hypothyroidism, Central,Hypothyroidism, Primary,Hypothyroidism, Secondary,Hypothyroidisms,Primary Hypothyroidisms,Secondary Hypothyroidisms,TSH Deficiencies,Thyroid Stimulating Hormone Deficiency,Thyroid-Stimulating Hormone Deficiencies
D008297 Male Males
D009200 Myocardial Contraction Contractile activity of the MYOCARDIUM. Heart Contractility,Inotropism, Cardiac,Cardiac Inotropism,Cardiac Inotropisms,Contractilities, Heart,Contractility, Heart,Contraction, Myocardial,Contractions, Myocardial,Heart Contractilities,Inotropisms, Cardiac,Myocardial Contractions
D009206 Myocardium The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow. Muscle, Cardiac,Muscle, Heart,Cardiac Muscle,Myocardia,Cardiac Muscles,Heart Muscle,Heart Muscles,Muscles, Cardiac,Muscles, Heart
D011945 Receptors, Angiotensin Cell surface proteins that bind ANGIOTENSINS and trigger intracellular changes influencing the behavior of cells. Angiotensin Receptor,Angiotensin Receptors,Angiotensin II Receptor,Angiotensin III Receptor,Receptor, Angiotensin II,Receptor, Angiotensin III,Receptor, Angiotensin
D006358 Hot Temperature Presence of warmth or heat or a temperature notably higher than an accustomed norm. Heat,Hot Temperatures,Temperature, Hot,Temperatures, Hot
D000064 Acclimatization Adaptation to a new environment or to a change in the old. Acclimation
D000804 Angiotensin II An octapeptide that is a potent but labile vasoconstrictor. It is produced from angiotensin I after the removal of two amino acids at the C-terminal by ANGIOTENSIN CONVERTING ENZYME. The amino acid in position 5 varies in different species. To block VASOCONSTRICTION and HYPERTENSION effect of angiotensin II, patients are often treated with ACE INHIBITORS or with ANGIOTENSIN II TYPE 1 RECEPTOR BLOCKERS. Angiotensin II, Ile(5)-,Angiotensin II, Val(5)-,5-L-Isoleucine Angiotensin II,ANG-(1-8)Octapeptide,Angiotensin II, Isoleucine(5)-,Angiotensin II, Valine(5)-,Angiotensin-(1-8) Octapeptide,Isoleucine(5)-Angiotensin,Isoleucyl(5)-Angiotensin II,Valyl(5)-Angiotensin II,5 L Isoleucine Angiotensin II,Angiotensin II, 5-L-Isoleucine
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D044140 Receptor, Angiotensin, Type 1 An angiotensin receptor subtype that is expressed at high levels in a variety of adult tissues including the CARDIOVASCULAR SYSTEM, the KIDNEY, the ENDOCRINE SYSTEM and the NERVOUS SYSTEM. Activation of the type 1 angiotensin receptor causes VASOCONSTRICTION and sodium retention. Angiotensin II Type 1 Receptor,Angiotensin Type 1 Receptor,Angiotensin Type 1a Receptor,Angiotensin Type 1b Receptor,Receptor, Angiotensin, Type 1a,Receptor, Angiotensin, Type 1b,Angiotensin AT1 Receptor,Angiotensin AT1a Receptor,Angiotensin AT1b Receptor,Angiotensin II Type 1a Receptor,Angiotensin II Type 1b Receptor,Receptor, Angiotensin II Type 1,Receptor, Angiotensin II Type 1a,Receptor, Angiotensin II Type 1b,AT1 Receptor, Angiotensin,AT1a Receptor, Angiotensin,AT1b Receptor, Angiotensin,Receptor, Angiotensin AT1,Receptor, Angiotensin AT1a,Receptor, Angiotensin AT1b

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