Background: Chronotropic incompetence has prognostic value of all-cause and cardiovascular mortality in both patients with asymptomatic and symptomatic ischemic heart disease (IHD), regardless of traditional risk factors. The aim of this study was to investigate the relationship between chronotropic response during exercise test and the development of ventricular arrhythmias. Methods: 153 pati...

Chronotropic incompetence is a common feature in Chagas' disease patients. New methodologies are now available to evaluate the chronotropic response in different subsets. The chronotropic-metabolic index (CMI) is one of these new indexes and quantifies the relationship between the increment of heart rate and the maximal oxygen consumption (VO2 max) during exercise testing. In normal subjects th...

decreased cardiac responsiveness to adrenergic stimulation has been observed in cholestatic liver disease, but the cause remains unclear. previous reports have suggested that nitric oxide overproduction might have a role in cholestasis-induced bradycardia via inhibition of l-type calcium channels. in the present study, the digoxin has been used to increase cardiac ca2+ transient in male sprague...

A mode of action of endothelin (ET) on spontaneous contractions was investigated in ring preparations of isolated bovine mesenteric lymphatics. ET-1 at concentrations between 10-10 and 10-9 M caused a dose-dependent increase in the frequency of spontaneous contractions. The specific ETA-receptor antagonist BQ-123 (5 × 10-7 M) caused a significant inhibition of the ET-1-induced positive chronotr...

Macrophage migration inhibitory factor acts via its intrinsic thiol-protein oxidoreductase activity to negatively regulate the neuronal chronotropic actions of angiotensin II in normotensive rat neurons. Because the chronotropic action of angiotensin II is potentiated in spontaneously hypertensive rat neurons, we investigated whether this negative regulatory mechanism is absent in these rats. A...

BACKGROUND Chronotropic incompetence (CI), defined as failure to achieve less than 80% of age-expected heart rate, is a predictor of mortality and adverse cardiovascular events and may confer a worse prognosis in elderly diabetic individuals. OBJECTIVE To evaluate the prognostic value of chronotropic incompetence (CI) in elderly diabetic patients considering endpoints with acute myocardial in...

Between 1958 and 1960 Astrand documented the normal heart rate response to exercise in healthy individuals and noted that the maximum heart rate decreased with age.' 2 A reduced cardiac chronotropic response to isoprenaline has been reported in elderly subjects and alterations in catecholamineadrenergic receptor interactions may be responsible for this change of cardiovascular regulation in the...

The perfusion of the sinus node artery in dogs in situ was performed. The selective administration of nicotine and DMPP into the sinus node artery induced a biphasic response, i.e., a negative chronotropic response followed by a positive one. Both compounds produced similar negative chronotropic responses, but positive responses were more markedly induced by DMPP than by nicotine. These negativ...

Sakai, Hiroshi, Fumitaka Ikomi, and Toshio Ohhashi. Effects of endothelin on spontaneous contractions in lymph vessels. Am. J. Physiol. 277 (Heart Circ. Physiol. 46): H459–H466, 1999.—A mode of action of endothelin (ET) on spontaneous contractions was investigated in ring preparations of isolated bovine mesenteric lymphatics. ET-1 at concentrations between 10210 and 1029 M caused a dose-depende...