Proximity of the vagus nerve to  a patent  ductus  arteriosus (PDA) can cause traction  or  entrapment  of vagus nerve during surgical closure of the in rare occasions. This can lead to a life threatening postoperative bradycardia. Herein, we report a case of bradycardia caused by unexpected irritation of the vagal trunk by the end of operation. The patient was managed by re-opening the chest, ...

We have recently shown that the intrinsic rate response to an increase in right atrial pressure is augmented when cardiac muscarinic receptors are activated. This present study examines the cardiac pacemaker response to vagal stimulation at different values of right atrial pressure in isolated rat right atrium and in the rabbit heart in situ. In the rat atrium, when pressure was raised in steps...

Stimulation of cardiopulmonary receptors with phenylbiguanide (PBG) elicits depressor cardiovascular reflex responses, including decreases in blood pressure and heart rate mediated in part by the brain stem parasympathetic cardiac neurons in the nucleus ambiguus (NAmb). The present study examined NAmb neurotransmitter mechanisms underlying the influence of electroacupuncture (EA) on the PBG-ind...

Endogenous opioids and nitric oxide (NO) are recognized modulators of cardiac function. Enkephalins and inhibitors of NO synthase (NOS) both produce similar interruptions in the vagal control of heart rate. This study was conducted to test the hypothesis that NO systems within the canine sinoatrial (SA) node facilitate local vagal transmission and that the endogenous enkephalin methionine-enkep...

The effect of cold on vagal action at the heart was studied in sheep, dogs and an isolated guinea pig atrial preparation. During cardiac output measurements in unanaesthetized sheep, by the thermodilution method, bradycardia was evoked on injection of cold indicator in eight of 12 sheep studied. This bradycardia was consistently evoked when blood pressure was increased, but not at normal blood ...

We tested the hypothesis that natriuretic peptide receptors (NPRs) that are coupled to cGMP production act in a similar way to nitric oxide (NO) by enhancing acetylcholine release and vagal-induced bradycardia. The effects of enzyme inhibitors and channel blockers on the action of atrial natriuretic peptide (ANP), brain-derived natriuretic peptide (BNP), and C-type natriuretic peptide (CNP) wer...

安孫子 保 The work was supported by a grant from the Ministry of Education in Japan. In spite of numerous reports on bradycardia produced by cardiac glycosides hitherto , the mechanism is not completely clarified. Ackermann (1) reported that early digitalis bradycardia was prevented by vagal severance or by administration of atropine. This observation has generally been ac cepted. Heymans and Heyma...

The vagotonic effect of chronic morphine on the parasympathetic control of the heart was examined in dogs treated with morphine for 2 wk. Because normal vagal function is critical to myocardial stability, the study was conducted to evaluate for potential impairments following chronic vagal stimulation. The hypothesis that persistent vagal outflow would result in a loss of vagal reserve and redu...

Arterial baroreflex function diminishes with age, but whether cardiopulmonary vagal reflexes are similarly altered with physiological aging has not been fully elucidated. In this study, predominantly cardiac high pressure mechanoreceptor-activated (ramp baroreflex) and cardiopulmonary chemoreceptor-activated (von Bezold-Jarisch reflex) vagal reflexes in conscious, instrumented rats were impaire...