Alpha1-adrenergic stress induces downregulation of Na+/Ca2+ exchanger in myocardial preparations from rabbits at physiological preload.

Alpha1-adrenergic stimulation and mechanical load are considered crucial for the expression of sarcolemmal Na+/Ca2+ exchanger (NCX1). However, the interaction between these processes is unknown. We investigated electrically stimulated (1 Hz, 1.75 mmol/L Ca2+) rabbit ventricular trabeculae at physiological preload under stimulation by the selective alpha1-agonist phenylephrine (PE, 10 micromol/L). Using quantitative real-time PCR, downregulation of mRNA to 76.5% (p