Retinoic acid increased expression of the Na+/Ca2+ exchanger in the heart and brain.

The Na+/Ca2+ exchanger (NCX) is an important calcium transport system, which regulates intracellular calcium homeostasis. In particular, NCX is highly expressed in the plasma membrane of excitable neuronal and cardiac cells. We report here that binding of retinoic acid enhances expression of the NCX1 in the rat cardiac atria, brain stem and hypothalamus, but not in cerebellum. Differences in the regulation of the NCX1 by retinoic acid might suggest that GATA4-retinoic acid inducible transcription factor is activated in the hypothalamus and brain stem, but not in the cerebellum. Our results support the idea that inducible transcription factors play an important role in the fine-tuning of local tissue calcium homeostasis.