The role of adrenergic and muscarinic receptors in stress-induced cardiac injury.

Takotsubo syndrome (TS) is a rare but dangerous disease that can be fatal. The pathogenesis of TS is not well understood because there is no animal model of TS that fully mimics TS. It has now been documented that stress exposure (24 h) of rats induced the state which is similar TS in human: contracture damage of myofibrils, elevation of the serum creatine kinase MB level, increased 99mTc-pyrophosphate (99mTc-PYP) accumulation in the heart, QTc interval prolongation, and contractility dysfunction of the heart. Immobilization stress resulted in an increase in coronary blood flow. Emotional stress increased the serum catecholamine level. Blockade of β1-adrenergic receptor (AR) prevented stress-induced cardiac injury (SICI). Blockade of β2-AR aggravated stress-induced cardiac injury. Stimulation of β2-AR increased cardiac tolerance to stress. Inhibition of β3-AR, α1-AR had no effect on SICI. Blockade of peripheral muscarinic receptors or α2-AR aggravated SICI. Pretreatment with the selective β1-AR antagonist atenolol attenuates stress-induced cardiac contractility dysfunction, but recovery of cardiac contractility is not complete. There is indirect evidence that circulating catecholamines play an important role in SICI. Consequently, the activation of β1-AR plays a significant role in SICI. However, there are other receptors which are also involved in SICI and require further investigation.