Type 1 and 2 IP3 Receptors Respond Differently to Catecholamines and Stress

Type 1 and 2 inositol 1,4,5-trisphosphate (IP3) receptors have been found in cardiac tissue, although they are localized in different types of cells. While the type 1 predominates in neuronal cells and cardiac ganglia, type 2 IP3 receptor is localized mainly in cardiomyocytes. In the heart, gene expression of the type 1 IP3 receptor is modulated by catecholamines, while type 2 is not affected. In this study we compared the effects of two stressors-cold exposure and hypoxia-on gene expression and protein levels of type 1 and 2 IP3 receptors. We found that both types of IP3 receptors were increased by these stressors, although the response of the type 2 IP3 receptor was delayed. We propose that regulation of these types of IP3 receptors in the heart might differ in control conditions and during stress.