Key result
Single-immobilization stress increased IP(3) receptor levels in cardiac atria but decreased them in adrenal medulla, whereas repeated stress significantly decreased levels across all tested tissues.
The study demonstrates that IP(3) receptor expression in cardiac and related tissues is differentially regulated by acute versus chronic stress.
Acute versus chronic stress differentially regulates cardiac IP3 receptors in animals; leaves open any role in human stress-related cardiovascular disease.
IP(3) receptors are intracellular calcium channels, releasing calcium from the sarcoplasmic reticulum. In the heart, IP(3) receptors of type 1 and 2 were found. These receptors predominate in atria, although they occur also in ventricles, as determined by real-time PCR and Western blot analysis. Single-immobilization stress was found to increase mRNA and/or protein levels of types 1 and 2 IP(3) receptors in cardiac atria. However, in stellate ganglia, which innervate the heart, no changes in the mRNA of the type 1 IP(3) receptors were observed after single-immobilization stress. In adrenal medulla, a moderate decrease in both mRNA and protein levels of IP(3) receptors was observed after single-immobilization exposure. After repeated immobilization, mRNA and protein levels of types 1 and 2 IP(3) receptors decreased significantly in all tested tissues. Our results point to different processing of the single stress in different tissues, while repeated stress results in rapid and significant decrease of the IP(3) receptors.
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Križanová et al. (2004) studied this question. Immobilization stress was evaluated on mRNA and protein levels of types 1 and 2 IP(3) receptors. Single-immobilization stress increased IP(3) receptor levels in cardiac atria but decreased them in adrenal medulla, whereas repeated stress significantly decreased levels across all tested tissues.
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