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The effect of cold exposure on beta-adrenegic signaling in the rat myocardium
Podojilová, Anna ; Novotný, Jiří (advisor) ; Ujčíková, Hana (referee)
and keywords The aim of this work was to evaluate the effect on rat myocardial β-adrenergic system of short-term (10 hours and 3 days) and long-term (5 weeks) cold exposure of rats with possible subsequent two-week recovery at normal temperature. The subtypes of β-adrenergic receptors (β-AR), their cognate G-proteins and adenylate cyclase have been characterized. β-AR are important components of cardiac regulatory mechanisms. They are involved in stimulating G-protein (Gs) and adenylate cyclase to increase cardiac contractility and frequency during stressful situations, including cold exposure. Heart tissue contains all three β-AR subtypes (β1-AR, β2-AR, β3-AR). While β1-AR couples with only Gs, β2-AR and β3-AR interact with the inhibitory G-protein (Gi). Electrophoresis and Western blotting showed a significant increase in β1-AR after a three-day exposure to cold. There was also a significant increase in β3-AR concentrations after a five-week cold exposure and this increase lasted for two weeks. There were no significant changes in the amnounts of β-AR cognate G-proteins (Gαs, Gβ, Gαi1/2 a Gαi3). In contrast, expression of adenylyl cyclase isoform V and VI significantly decreased during short-term exposure to cold. Using the saturation experiment with the β-antagonist [3H]CGP 12177, β-AR were...
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