Karl P. Undesser

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This study compares the effect of arginine-vasopressin with phenylephrine on arterial pressure, heart rate, and renal sympathetic nerve activity in conscious rabbits with and without functional arterial baroreflexes and in rabbits with lesions of the area postrema. In intact rabbits, progressive infusions of arginine-vasopressin result in large decreases in(More)
The purpose of this study was to assess the effect of rapid baroreceptor resetting on the baroreflex control of renal sympathetic nerve activity in conscious rabbits. Renal sympathetic nerve activity was recorded and used as an index of the efferent limb of the baroreflex. Heart rate and arterial pressure were also recorded. Arterial pressure was raised(More)
Effects of arginine vasopressin (AVP) on inhibition of renal sympathetic nerve activity (RSNA) during activation of cardiopulmonary reflexes by volume expansion were examined in conscious sinoaortic-denervated rabbits. The role of the area postrema in mediating these effects was also evaluated in rabbits subjected to area postrema lesion. Animals were(More)
The purpose of this study was to examine the role of angiotensin II (ANG II), arginine vasopressin (AVP), and neurogenic mechanisms in maintaining arterial pressure (MAP) in conscious water-deprived rabbits. Water deprivation produced marked increases in plasma renin activity and the concentration of AVP; however, plasma catecholamine concentrations were(More)
The objective of this randomized, double-blind, placebo-controlled clinical trial was to test the efficacy and safety of a new sustained-release preparation of the antiarrhythmic drug propafenone (propafenone SR) in reducing the frequency of symptomatic arrhythmia recurrences in patients with atrial fibrillation (AF). Patients with a history of symptomatic(More)
Activation of the area postrema by either electrical stimulation or chemical application of L-glutamate has been shown to result in an enhancement of cardiovascular baroreflexes similar to that seen with systemic infusions of arginine vasopressin (AVP). In addition, it has been found that the effects of AVP on baroreflex inhibition of renal sympathetic(More)
The effect of increased arterial pressure on aortic depressor nerve activity was studied in the conscious rabbit. Aortic baroreceptor resetting was observed following 15 min of sustained pressure elevation. At 15 min, there was a significant increase in the threshold arterial pressure for aortic nerve activity, but peak nerve activity did not change. This(More)
This study compares the effect of arginine-vasopressin and phenylephrine on renal sympathetic nerve activity, arterial pressure, and heart rate in vehicle- and intraventricular 6-hydroxydopamine-treated conscious rabbits. In addition, this study examines the involvement of forebrain structures on these variables. In vehicle-treated rabbits, compared to(More)
Background: The upper limit of vulnerability (ULV) is the stimulus strength above which ventricular fibrillation cannot be induced, even when the stimulus occurs during the vulnerable period of the cardiac cycle. Determination of ULV using T-wave shocks during ventricular pacing has been shown to closely correlate with the defibrillation threshold (DFT) at(More)
This study compares the effect of arginine-vasopressin and phenylephrine on renal sympathetic nerve activity, arterial pressure, and heart rate in vehicleand intraventncular 6hydroxydopamine-treated conscious rabbits In addition, this study examines the involvement of forebram structures on these variables. In vehicle-treated rabbits, compared to(More)
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