Inotropic, chronotropic, and dromotropic effects mediated via parasympathetic ganglia in the dog heart

Abstract

Some parasympathetic ganglionic cells are located in the epicardial fat pad between the medial superior vena cava and the aortic root (SVC-Ao fat pad) of the dog. We investigated whether the ganglionic cells in the SVC-Ao fat pad control the right atrial contractile force, sinus cycle length (SCL), and atrioventricular (AV) conduction in the autonomically decentralized heart of the anesthetized dog. Stimulation of both sides of the cervical vagal complexes (CVS) decreased right atrial contractile force, increased SCL, and prolonged AV interval. Stimulation of the rate-related parasympathetic nerves to the sinoatrial (SA) node (SAPS) increased SCL and decreased atrial contractile force. Stimulation of the AV conduction-related parasympathetic nerves to the AV node prolonged AV interval. Trimethaphan, a ganglionic nicotinic receptor blocker, injected into the SVC-Ao fat pad attenuated the negative inotropic, chronotropic, and dromotropic responses to CVS by 33 approximately 37%. On the other hand, lidocaine, a sodium channel blocker, injected into the SVC-Ao fat pad almost totally inhibited the inotropic and chronotropic responses to CVS and partly inhibited the dromotropic one. Lidocaine or trimethaphan injected into the SAPS locus abolished the inotropic responses to SAPS, but it partly attenuated those to CVS, although these treatments abolished the chronotropic responses to SAPS or CVS. These results suggest that parasympathetic ganglionic cells in the SVC-Ao fat pad, differing from those in SA and AV fat pads, nonselectively control the atrial contractile force, SCL, and AV conduction partially in the dog heart.

Catheter Ablation of Cardiac Fat Pads Attenuates Bezold-Jarisch Reflex in Dogs

“…found that injecting 6‐hydroxy quaternary amine into the 3 FPs could abolish AV block and decrease of sinus rate induced by vagal stimulation. Tsuboi et al 16 . and Chiou and Zipes 17 found that destroying the vagus ganglia in the 3 FPs attenuated the vagal stimulation‐induced negative chronotropic, inotropic, and dromotropic effects on the heart.…”

The Remodeling of Connexins Localized at Pulmonary Vein – Left Atria in Triggering and Maintenance of Atrial Fibrillation

“…What is more, the autonomic nervous system has a crucial role in the genesis, maintenance and abruption of atrial fibrillation (Duffy& Wit, 2008;Sandres et al,2004), and there is a fat pad localized in superior vena cava and the root of aorta as the origin of cardiac nerve, being called SVC-Ao fat pad (Kapa et al,2010;Volders ,2010;Ji et al,2010). The mechanism of atrial fibrillation involves multiple effects (Chiou et al,1997;Tsuboi et al,2000;Hoffmann et al, 2006;Haissaguerre et al1998;Wit & Boyden,2007), the expression of connexins is changed and is associated with increased propensity for arrhythmias (Kanagaratnam et al, 2002, Herve et al, 2007, Stergiopoulos et al, 1999, Verheule S et al, 2002, Kanagaratnam et al, 2007Valiunas et al,2001;Cottrell et al,2002;Elenes et al,1999). Pulmonary veins and left atria are the primary structure of genesis, persistence of atrial fibrillation.…”

Location and variability of epicardiac ganglia in human fetuses

“…Intrinsic cardiac nervous system (ICNS) plays a crucial role in regulation of heart rate, contractility and tone of the coronary vessels (Young et al 1987;Ardel 1994;Baumgart and Heusch 1995;Furukawa et al 1997;Dickerson et al 1998;Feigl 1998;Tsuboi et al 2000;Randall et al 2003;Olufsen et al 2005). In neonates and infants, the intrinsic neural pathways are considered to be important for radiofrequency ablation that is performable in cases of incessant supraventricular and atrioventricular nodal re-entry tachycardia (Osborn et al 1999;Blaufox et al 2001;Shah et al 2001;Oudijk et al 2003;Van Hare et al 2004).…”