AIMS: Release of @entity1063 (NE) from sympathetic neurons enhances heart rate (HR) and developed force through activation of b-adrenergic receptors, and this sympathoexcitation is a key risk for the generation of @entity943 . Studies of b-adrenergic modulation of cardiac function typically involve the administration of exogenous b-adrenergic receptor agonists to directly elicit global b-adrenergic receptor activation by bypassing the involvement of sympathetic nerve terminals. In this work, we use a novel method to activate sympathetic fibres within the myocardium of Langendorff-perfused hearts while measuring changes in electrical and mechanical function. METHODS AND RESULTS: The light-activated optogenetic protein channelrhodopsin-2 (ChR2) was expressed in @entity19 catecholaminergic sympathetic neurons. Sympathetic fibres were then photoactivated to examine changes in contractile force, HR, and cardiac electrical activity. Incidence of @entity943 was measured with and without exposure to photoactivation of sympathetic fibres, and hearts were optically mapped to detect changes in action potential durations and conduction velocities. Results demonstrate facilitation of both developed force and HR after photostimulated release of NE, with increases in contractile force and HR of 34.5    5.5 and 25.0    9.3%, respectively. Photostimulation of sympathetic fibres also made hearts more susceptible to @entity943 , with greater incidence and severity. In addition, optically mapped action potentials displayed a small but significant shortening of the plateau phase (-5.5    1.0 ms) after photostimulation. CONCLUSION: This study characterizes a powerful and clinically relevant new model for studies of @entity943 generated by increasing the activity of sympathetic nerve terminals and the resulting activation of myocyte b-adrenergic receptors.

Optogenetic release of XXXX from cardiac sympathetic neurons alters mechanical and electrical function.

@entity19 :: ('10090', 'Species') :: ['murine'] @entity1063 :: ('MESH:D009638', 'Chemical') :: ['norepinephrine'] @entity943 :: ('MESH:D001145', 'Disease') :: ['arrhythmia', 'cardiac arrhythmias']
@entity1063 :: (MESH:D009638,Chemical) :: ['norepinephrine']
