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This study aimed firstly to compare the in vivo cardiovascular effects of exogenously administered and of endogenously released noradrenaline; secondly to characterize the adrenoceptors mediating these responses; thirdly to assess the influence of parasympathetic tone on the cardiovascular effects of noradrenaline. In two randomised placebo-controlled(More)
The M1 muscarinic receptor antagonist pirenzepine in low doses decreases resting heart rate; this effect declines with age (Poller, U., G. Nedelka, J. Radke, K. Pönicke, and O.-E. Brodde. 1997. J. Am. Coll. Cardiol. 29:187-193). To study possible mechanisms underlying this effect, we assessed (a) in six young (26 yr old) and six older volunteers (61 yr(More)
1. A substantial body of evidence has accumulated that beta-adrenoceptor mediated increases in human lymphocyte cyclic AMP can inhibit activation of resting lymphocytes. The aim of this study was to determine whether this effect might desensitize during chronic beta-adrenoceptor agonist treatment. We assessed the effects of 2 weeks treatment with the beta(More)
OBJECTIVES The M1-muscarinic receptor antagonist pirenzepine in low doses (<1 mg intravenously) decreases heart rate. We investigated whether these effects of pirenzepine differ in volunteers with activated cardiac beta1-adrenergic receptors versus activated cardiac beta2-adrenergic receptors. METHODS In 17 male volunteers (25 +/- 1 years) we studied(More)
OBJECTIVES This study was conducted to determine possible age-dependent changes in the responsiveness of human cardiac muscarinic receptors. BACKGROUND It is well known that the baroreflex activity decreases with aging. However, the mechanisms underlying this phenomenon are not completely understood at present. METHODS In six healthy young (mean(More)
The M 1 muscarinic receptor antagonist pirenzepine in low doses decreases resting heart rate; this effect declines with age (Poller, U., G. Nedelka, J. Radke, K. Pönicke, and O.-E. Brodde. 1997. J. Am. Coll. Cardiol. 29:187–193). To study possible mechanisms underlying this effect, we assessed ( a ) in six young (26 yr old) and six older volunteers (61 yr(More)
OBJECTIVES The purpose of this study was to elucidate whether cardiac beta-adrenergic effects may be blunted in patients on maintenance hemodialysis (HD) and may help to explain autonomic dysfunction. BACKGROUND Patients on HD often suffer from autonomic dysfunction. METHODS We investigated the cardiovascular response of five HD patients (age:(More)
BACKGROUND In patients with chronic heart failure cardiac beta 1-adrenoceptors are desensitized whereas beta 2-adrenoceptors are only marginally affected. The mechanism underlying this differential regulation is not known. OBJECTIVES To find out whether or not human cardiac beta 2-adrenoceptors might be 'resistant' to agonist-induced desensitization and(More)
The aim of this study was to find out whether cardiac responses to the beta-adrenoceptor antagonists with intrinsic sympathomimetic activity (ISA) xamoterol and celiprolol are mediated by cardiac beta1- or beta2-adrenoceptors or both. For this purpose we assessed, in six healthy male volunteers, the effects of xamoterol (100 and 200 mg, p.o.) and celiprolol(More)
The aim of this study, carried out in six elder healthy volunteers (mean age: 61 years), was to determine the influence of muscarinic receptor blockade with atropine (15 µg/kg i.v. loading dose followed by 0.15 µg/kg/min by i.v. infusion) on the effects of i.v. infusions of noradrenaline (5 incremental doses of 10-120 ng/kg/min) or tyramine, that releases(More)