Journal ArticleDOI
Influence of beta 1- versus beta 2-adrenoceptor blockade on left ventricular function in humans.
TLDR
In normal young subjects, global LV pump function is not affected by beta 1- or by beta 2-blockade, despite the negative chronotropic effect of both drugs.Abstract:
Pharmacological and radio-ligand binding studies have recently indicated the existence of beta 2-adrenoceptors in the human heart. Their physiological role, however, remains to be elucidated. The present study investigated in 17 normal, young volunteers the effect on resting left ventricular (LV) function of two types of beta-blockers; a predominant beta 1-adrenoceptor antagonist (atenolol, 50 mg once daily) and ICI 118,551 (20 mg t.i.d.), a new, predominant beta 2-antagonist. LV function was assessed using M-mode echocardiograms and systolic time intervals. Atenolol, ICI 118,551, and placebo were given according to a randomized, double-blind, cross-over protocol. As compared with placebo, both drugs caused a decrease in resting heart rate, but the reduction by ICI 118,551 was less pronounced. Systolic blood pressure was only reduced by atenolol 8 mm Hg on average. Cardiac output was decreased to the same extent following treatment with atenolol (-20%) as after ICI 118,551 (-17%). These decreases in cardiac output were related to the beta-blocker-induced bradycardia, since stroke volumes were not affected during either selective beta 1- or beta 2-blockade. In addition, all other echocardiographic variables reflecting LV pump function, such as fractional shortening, velocity of diameter change and of displacements, pre-ejection period, and the ratio of PEP/LVET, were not different from placebo. We conclude that in normal young subjects, global LV pump function is not affected by beta 1- or by beta 2-blockade, despite the negative chronotropic effect of both drugs.(ABSTRACT TRUNCATED AT 250 WORDS)read more
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Journal ArticleDOI
Do β-blockers prolong survival in heart failure only by inhibiting the β1-receptor? A perspective on the results of the COMET trial
TL;DR: Analysis of the results of the recently completed COMET trial suggests that the observed difference in the mortality effects of metoprolol and carvedilol is not related to a differences in the magnitude or time course of their β 1 -blocking effects but instead reflect antiadrenergic effects of carveilol in addition toβ 1 -blockade.
Journal ArticleDOI
Effect of bisoprolol and atenolol on endurance exercise capacity in healthy men.
Luc Vanhees,Johan Defoor,Dirk Schepers,Paul Lijnen,Brigitte Y.M. Peeters,Paul H.L. Lacante,Robert Fagard +6 more
TL;DR: It is concluded that both drugs affect endurance exercise capacity in young, normotensive men, with a tendency to a smaller reduction during bisoprolol treatment.
Journal ArticleDOI
Nonadrenal epinephrine-forming enzymes in humans. Characteristics, distribution, regulation, and relationship to epinephrine levels.
TL;DR: It is concluded that PNMT and NMT are widely distributed in human tissues, that they may synthesize E in vivo and are influenced by glucocorticoid and thyroid hormones.
Journal ArticleDOI
Is the ISA of pindolol beta 2‐adrenoceptor selective?
W. H. Aellig,BJ Clark +1 more
TL;DR: The evidence available suggests that although pindolol blocks both beta 1- and beta 2-subtypes, it selectively stimulatesbeta 2-adrenoceptors.
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