The electrocardiogram (ECG) characteristics of athletes have recently become a topic of intensive study to accurately identify dangerous and benign alterations in this special population. These subjects develop a high-vagal tone and consequently sinus bradycardia and different degrees of atrioventricular (AV)-block, but it is difficult to determine how much is too much, and the indications for ...

The vasovagal response is the development of inappropriate cardiac slowing and arteriolar dilatation. Vasovagal responses reflect autonomic neural changes: bradycardia results from sudden augmentation of efferent vagal activity, and hypotension results from sudden reduction or cessation of sympathetic activity and relaxation of arterial resistance vessels. Two different neural pathways are thou...

We demonstrated previously that atrial natriuretic peptide (ANP) enhances reflex bradycardia to intravenous serotonin [5-hydroxytryptamine (5-HT)] (von Bezold-Jarisch reflex) in rats. To determine whether 1) ANP affects this cardiopulmonary vagal reflex in another species and 2) B-type (BNP) and C-type (CNP) natriuretic peptides share with ANP the ability to modulate this reflex, we used intrav...

We determined the excitatory effects of direct nucleus tractus solitarii injection of angiotensin peptides after the sinoaortic nerves were cut unilaterally in rats under halothane anesthesia. Twenty-four hours later, recordings of mean arterial pressure and heart rate were obtained during injections of 2.5 ng angiotensin II or angiotensin-(1-7) in chloralose-urethane-anesthetized rats. Both pe...

The baroreflex sensitivity (BRS) and the heart rate variability (HRV) were studied in conscious rats after myocardial infarction (MI; induced by coronary artery ligation) and after sham operation (SH). BRS was determined by linear regression of R-R interval vs. arterial pressure changes induced by nitroprusside or methoxamine (intravenous bolus). HRV was calculated from 3-min electrocardiogram ...

Contraction and relaxation of airway smooth muscles is mediated, in part, by G protein-coupled receptors (GPCRs) and dysfunction of these receptors has been implicated in asthma. Phosphorylation of GPCRs, by G protein-coupled receptor kinase (GRK), is an important mechanism involved in the dampening of GPCR signaling. To determine whether this mechanism might play a role in airway smooth muscle...

Circulating leptin is elevated in some forms of obesity-related hypertension, associated with impaired baroreflex function. Leptin receptors are present on vagal afferent fibers and neurons within the solitary tract nucleus, providing an anatomic distribution consistent with baroreflex modulation. Although solitary tract nucleus microinjection of 144 fmol/60 nL of leptin had no significant effe...

Using bioinformatic analyses of full-length, enriched human cDNA libraries, we recently identified salusins, multifunctional related peptides ubiquitously expressed in major human tissues. Salusins cause transient and profound hypotension when injected intravenously to rats, the hypotensive effect of salusin-beta being especially striking. However, the mechanisms of this hypotensive action rema...

Angiotensin II is a potent vasoconstrictor and has profound effects on autonomic neural mechanisms in experimental animals. Human carotid baroreflex control of arterial pressure and heart period was examined before and after acutely decreasing angiotensin II levels by administering 50 mg of oral captopril, an angiotensin converting enzyme inhibitor. Carotid baroreceptor stimuli were delivered b...