The role of the external cuneate nucleus (ECN) in the control of heart rate was systematically investigated in 26 chloralosed and 2 decerebrated, paralyzed, and artifically ventilated cats. Electrical stimulation of histologically verified sites in the ventral ECN and dorsal spinal trigeminal tract elicited a marked decrease in heart rate, with threshold currents of 5-25 muA and an optimal freq...

Previously, we found that the nitrate synthesized from glycerin, 2-nitrate-1,3-dibuthoxypropan (NDBP), increased NO levels in rat aortic smooth muscle cells, inducing vasorelaxation in mesenteric artery. However, its effects on blood pressure and heart rate as well as on autonomic function were not investigated. This study evaluated the action of NDBP on these cardiovascular parameters in spont...

Embolization of the sinus node artery was accomplished in dogs by injecting rapidly hardening vinyl latex into the sinus node artery. Embolization immediately shifted the pacemaker to a junctional focus; however, with time postoperatively, the pacemaker shifted to an atrial site. Variable episodes of pacemaker failure, sinoatrial block, junctional rhythm, wandering atrial pacemaker and idiovent...

AIMS Previous work provided indirect evidence that the neurotrophic factor neurturin (NRTN) is required for normal cholinergic innervation of the heart. This study used nrtn knockout (KO) and wild-type (WT) mice to determine the effect of nrtn deletion on cardiac cholinergic innervation and function in the adult heart. METHODS AND RESULTS Immunohistochemistry, confocal microscopy, and quantit...

The vasovagal response is characterized by an inappropriate combination of bradycardia and paradoxical vasodilation. During a general or neuraxial anesthesia-induced sympathectomy, a sudden vagal activation and/or an acute reduction in sympathetic tone can cause serious vasovagal responses. Neuraxial anesthesia for Cesarean section may trigger vasovagal response, due to multiple risk factors; h...

Greenwood and Finkelstein (I964), in a review of 223 patients including their own and those reported by other authors in the preceding 50 years, listed the aetiological factors resulting in sinuatrial block as increased vagal tone, infections in childhood, including rheumatic carditis, diphtheria, and influenza and, in adults, ischaemic heart disease and digitalis intoxication. However, in thei...

Distortion of the upper airway by negative transmural pressure (UANP) causes reflex vagal bradycardia. This requires activation of cardiac vagal preganglionic neurons, which exhibit postinspiratory (PI) discharge. We hypothesized that UANP would also stimulate cranial respiratory motoneurons with PI activity. We recorded 32 respiratory modulated motor units from the recurrent laryngeal nerve of...

Neural control of free and forced diving bradycardia and peripheral resistance was studied in the muskrat (Ondatra zibethicus) by means of acute pharmacological blockade with the muscarinic blocker atropine, the alpha-adrenergic blocker phentolamine and the beta-adrenergic blockers nadolol and propranolol. Saline injection was used as a control. Heart rate in control animals increased before vo...

1. the oesophageal plexus is in the structure and arrangement of its larger branches constant. ·2 . two trunks arise from the oesophageal plexus, the . anterior vagal trunk and the posterior vagal trunk; each trunk contains fibers of both left and right vagi nerves. 3. these vagal trunks in the majority of instances pass through the oesophageal opening of the diaphragm each in the form of the o...

BACKGROUND In normal, conscious dogs, systemic injection of adenosine causes arterial hypotension and a baroreceptor reflex tachycardia mediated in part by withdrawal of vagal tone from the sinoatrial node. After vagal section or muscarinic receptor blockade, however, adenosine injection causes bradycardia via a direct sinoatrial node inhibition. Because cardiac failure is marked by a loss of v...