A patient is described with acute dysautonomia associated with Hodgkin's disease. Testing of cardiovascular reflex control showed that this patient had a rare manifestation of autonomic cardiovascular neuropathy, namely intact parasympathetic heart rate control in combination with a sympathetic postganglionic lesion affecting the control of the vascular tree.

Hyperpolarization and Cyclic Nucleotide (HCN) -gated channels represent the molecular correlates of the "funny" pacemaker current (I(f)), a current activated by hyperpolarization and considered able to influence the sinus node function in generating cardiac impulses. HCN channels are a family of six transmembrane domain, single pore-loop, hyperpolarization activated, non-selective cation channe...

The present article contains a brief review on the role of vasopressinergic projections to the nucleus tractus solitarii in the genesis of reflex bradycardia and in the modulation of heart rate control during exercise. The effects of vasopressin on exercise tachycardia are discussed on the basis of both the endogenous peptide content changes and the heart rate response changes observed during r...

Parasympathetic regulation of sinoatrial node (SAN) pacemaker activity modulates multiple ion channels to temper heart rate. The functional role of the G-protein-activated K(+) current (IKACh) in the control of SAN pacemaking and heart rate is not completely understood. We have investigated the functional consequences of loss of IKACh in cholinergic regulation of pacemaker activity of SAN cells...

Alpha-2 adrenoreceptor stimulation profoundly augments baroreflex-mediated bradycardia presumably through parasympathetic activation. We tested the hypothesis that endogenous alpha-2 adrenergic tone mediates a similar response. In 10 healthy men (age: 33+/-3 years; body mass index: 24+/-1.3 kg/m(2)), we determined baroreflex control of heart rate and sympathetic traffic after ingestion of the s...

We studied the contribution of carotid vs. extracarotid baroreceptors in control of heart rate in normal humans. We measured heart interval (HI) and arterial pressure during steady-state infusion of phenylephrine (PE). PE increased mean arterial pressure (MAP) by 13 +/- 2 mmHg (mean +/- SEM; n = 10) and thus stimulated both carotid and aortic baroreceptors. Neck pressure (NP) was applied during...

BACKGROUND The objective of this study was to determine the effect of inspiratory resistance through an impedance threshold device (ITD) on orthostatic tolerance in patients with postural tachycardia syndrome. We hypothesized that the ITD would result in a greater negative intrathoracic pressure to enhance cardiac venous return, improve stroke volume, and reduce heart rate in these patients. ...

AIMS B2-agonists and anticholinergic drugs may alter cardiac autonomic modulation. The aim of this study was to investigate the effects of inhaled salbutamol and ipratropium bromide on heart rate variability (HRV). METHODS AND RESULTS A randomized, double-blind, crossover design study was conducted on 13 healthy volunteers. Salbutamol, ipratropium or placebo was administered in three differen...

PURPOSE Atrial fibrillation (AF) is one of the most common types of sustained dysrhythmia and there are some disagreements about its treatment. The goals of AF treatment include the control of ventricular rate, the establishment of sinus rhythm and the prevention of thromboembolic events. In this study, the effect of verapamil was compared to digoxin on heart rate control in patients with AF. ...

We have studied the cardiac chronotropic responses to the Valsalva maneuver and to dynamic exercise of twenty chronic chagasic patients with normal left ventricular function and no segmental wall abnormalities by two-dimensional echocardiogram. The absolute increase in heart rate of the patients (Δ = 21.5 ± 10 bpm, M±SD) during the maneuver was significantly diminished when compared to controls...