Cardiac-protective effects and the possible mechanisms of alatamine during acute myocardial ischemia.

Alatamine is a constituent in the extract of a traditional herbal medicine Ramulus euonymi widely used for cardiac protection. However, its precise effects remain unclear. In the present study, we found that alatamine was able to reduce acute myocardial ischemia (AMI)-induced cardiac dysfunction in a rat model, as reflected by significantly restored electrocardiograms, M-mode echocardiograms, and left ventricular hemodynamics. Also, Nagar Olsen staining revealed that alatamine markedly reduced AMI-induced cardiac injury and cardiac myocyte apoptosis. TUNEL and caspase-3 activity assay showed that cardiac myocytes underwent significant apoptosis during AMI, and levels of LDH and CK-MB increased in the serum. However, such changes were significantly inhibited by pre-administration of alatamine. Furthermore, such anti-apoptotic effects of alatamine was also confirmed in a cardiac myocyte model of isoproterenol (ISO)-induced damage. Mechanistically, it was also found that alatamine improved the expression and activity of sarcoplasmic/endoplasmic reticulum Ca(2+) ATPase (SERCA), which were inhibited during AMI, promoting contractility and relaxation. Meanwhile, alatamine decreased Bax and increased Bcl-2 expressions both in vivo and in vitro, therefore inhibiting cardiac myocyte apoptosis and preventing cardiac dysfunction caused by AMI at the cellular level. The present study revealed the beneficial role of alatamine in cardiac protection and highlighted it as a potential therapeutic reagent for reduction of AMI-induced cardiac injury.