The effect of metoclopramide on presynaptic dopamine receptors was investigated in the cat cardioaccelerator nerve preparation. Metoclopramide, a substituted benzamide derivative, antagonized inhibitory action of apomorphine on positive chronotropic responses induced by sympathetic nerve stimulation in cat hearts, in vivo. Neither phentolamine, an alpha-adrenergic blocking agent, nor indomethac...

BACKGROUND Chronotropic index is a standardized measure of heart rate (HR) increment during exercise that reflects the combined effects of age, resting HR, and physical fitness. Low chronotropic index has been reported to predict disease and death. We tested whether temporal change in chronotropic index over 7 years influenced risk of cardiovascular death through up to 28 years. METHODS AND R...

BACKGROUND Despite abundant evidence of increased morbidity and mortality, chronotropic incompetence (CI) is not a routine diagnosis well defined in protocols of cardiac evaluation and its clinical importance is still underestimated. OBJECTIVE To evaluate the clinical and echocardiographic parameters associated with HF in non-elderly patients submitted to stress echocardiography (SE). METHO...

Chronotropic incompetence (CI) has been proven to be an important factor in the diagnosis and management of cardiovascular diseases. In this paper, we extend the existing CI parameters and propose chronotropic competence indices (CCI) to describe the exercise response of the cardiopulmonary system. A cardiac chronotropic competence Test (3CT), dedicated to CCI measurement using a wearable devic...

CHIBA, S. and HASHIM0TO, K. Effect of Aminophylline on the SA Node of the Dog Heart in situ. Tohoku J. exp. Med., 1973, 109 (2), 203-204 -The perfusion of the sinus node artery in 9 dogs in situ was performed. The selective injection of aminophylline into the sinus node artery induced a positive chronotropic response. The positive chronotropic response to aminophylline was suppressed not only b...

Inability to reach 85% of the predicted maximal heart rate for age during exercise stress testing (chronotropic incompetence) has been considered indicative of an uninterpretable or inadequate test. A new study from the Cleveland Clinic suggests that a submaximal heart rate response to exercise may be a significant independent risk factor for all-cause and cardiovascular death in individuals wi...

Positive chronotropic effects from the combination of ouabain administration and rapid stimulation were sought in the atrium and ventricle of ten anesthetized vagotomized dogs with intact atrioventricular conduction during the infusion of ouabain (1 MgAg min") until the onset of ventricular tachycardia. Sinus rhythm was interrupted every minute by 15 seconds of atrial pacing at either 150 or 20...

Transmural stimulation of, or application of nicotine to, the isolated rabbit sinoatrial (SA) node resulted in initial negative and late positive chronotropy. Simultaneous application of acetylcholine and norepinephrine produced a similar biphasic chronotropic effect. These procedures produced an initial increase in cyclic guanosine 3':5'-monophosphate (cyclic GMP) and a delayed elevation in cy...

Gastric emptying depends on functional coupling of slow waves between the corpus and antrum, to allow slow waves initiated in the gastric corpus to propagate to the pyloric sphincter and generate gastric peristalsis. Functional coupling depends on a frequency gradient where slow waves are generated at higher frequency in the corpus and drive the activity of distal pacemakers. Simultaneous intra...

The effects of piretanide and furosemide on systemic arterial blood pressure and heart rate were examined in the anesthetized dog and the effects on atrial rate and contractile force were assessed in isolated atrial muscle perfused with heparinized arterial blood from a donor dog. When piretanide was administered intravenously to intact dogs, the depressor and bradycardic responses were produce...