Functional Characterization of Cysteinyl Leukotriene CysLT2 Receptor on Human Coronary Artery Smooth Muscle Cells

Cysteinyl leukotrienes (LTC4, LTD4, and LTE4) are a class of biologically active lipids that exert potent effects on the heart. To assess their roles, we investigated the distribution of their receptors, CysLT1 and CysLT2, in the cardiovascular system. CysLT2 mRNA was detected at high levels in the human atrium and ventricle and at intermediate levels in the coronary artery, whereas CysLT1 mRNA was barely detected. Further analysis by in situ hybridization revealed that CysLT2 mRNA was expressed in myocytes, fibroblasts, and vascular smooth muscle cells, but not in endothelial cells. When human coronary smooth muscle cells were stimulated with LTC4, the intracellular calcium concentration increased in a dose-dependent manner, and this action was partially inhibited by nicardipine. Additionally, these cells showed chemotactic responses to LTC4. This is the first report on the physiological role of CysLT2, and the findings suggest that CysLT2 has biological significance in the cardiovascular system.