نتایج جستجو برای: vagal bradycardia
تعداد نتایج: 13543 فیلتر نتایج به سال:
Preganglionic vagal motoneurones supplying the heart of the dogfish have been located in the medulla by antidromic stimulation of the central cut end of the branchial cardiac branch of the vagus. They supplied axons with conduction velocities between 4.75 and 16.3 m s-1, which is similar to mammalian B fibres. Motoneurones were found in two locations: the rostromedial (N = 5) and lateral (N = 1...
Potent cardioinhibitory vagal reflex resulting in bradycardia and hypotension has been observed under particular conditions of transmural inferior ischemia and its reperfusion, such as those observed with acute infarction. However, whether exercise-induced ischemia with ST depressions that is subendocardial and that might be recurrently experienced in daily activities can evoke this reflex rema...
Parasympathetic control of the heart is attenuated in heart failure (HF). We investigated possible mechanisms and sites of altered vagal control in dogs with HF induced by rapid pacing. Muscarinic blockade reduced the R-R interval by 308 ms in controls but only by 32 ms in HF, indicating low levels of resting vagal tone. Vagomimetic doses of atropine sulfate prolonged the R-R interval by 109 ms...
The current study applies a neurophysiological model based on the Polyvagal Theory (Porges, 1995) to interpret fetal heart rate patterns. Beat-to-beat heart rate data from 7 fetuses monitored during the first and second stages of labor were analyzed. Transitory heart rate accelerations and reduced beat-to-beat variability reliably preceded heart rate decelerations. The data are interpreted with...
BACKGROUND Alterations in muscarinic receptor expression and acetylcholinesterase (AchE) activity have been observed in tissues from Sudden Infant Death Syndrome (SIDS). Vagal overactivity has been proposed as a possible cause of SIDS as well as of vasovagal syncopes. The aim of the present study was to seek whether muscarinic receptor overexpression may be the underlying mechanism of vagal hyp...
Hypertension is associated with reduced cardiac vagal activity and decreased atrial guanylate cyclase and cGMP levels. Neuronal production of NO facilitates cardiac parasympathetic transmission, although oxidative stress caused by hypertension may disrupt this pathway. We tested the hypothesis that peripheral vagal responsiveness is attenuated in the spontaneously hypertensive rat (SHR) because...
Hypertension is associated with reduced cardiac vagal activity and decreased atrial guanylate cyclase and cGMP levels. Neuronal production of NO facilitates cardiac parasympathetic transmission, although oxidative stress caused by hypertension may disrupt this pathway. We tested the hypothesis that peripheral vagal responsiveness is attenuated in the spontaneously hypertensive rat (SHR) because...
Pretreatment with MK-801, a non-competitive N-methyl-D-aspartate (NMDA) antagonist, failed to protect the vagal component of reflex bradycardia from 5-min global cerebral ischemia in dogs under pentobarbital anesthesia. On the other hand, MK-801 completely prevented the development of the post-ischemic cerebral hypoperfusion without affecting the cerebral blood flow in sham-operated animals. Th...
BACKGROUND Prolonged ventricular asystole is a rare vagal reaction caused by hydrocodone use. Sinus bradycardia is a characteristic presentation of the vasovagal response; examples of other presentations include arrest or atrioventricular block. Physicians need to be aware of ventricular asystole due to vagally-mediated atrioventricular block caused by hydrocodone or other opiates. CASE REPOR...
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