Key result
Beta-blockers suppress atrial arrhythmias and arrest via both beta-blockade and membrane stabilization.
Why the study?
The comparative effects of various beta-blockers on beta-blocking, local anaesthetic, membrane stabilizing, and strophanthin-G cardiotoxicity antagonizing actions in guinea-pig atria were not fully characterized.
Answers are grounded in this paper and cite their sources.
Guinea-pig comparisons of beta-blocker potency and antiarrhythmic effects warrant caution in extrapolation; leaves open human validation.
The influence of alprenolol, carteolol, indenolol, pindolol, practolol, and propranolol on the effect of isoproterenol in isolated guinea-pig atrial contraction rate was examined comparing their beta-blocking actions, and their influence on the responses of guinea-pig cornea and dorsal skin to the mechanical stimulation was tested comparing their local anaesthetic actions. Further, the effect of each drug to prevent the arrhythmic contractions, induced by electrical stimulation in spontaneous rhythmic contractions in isolated guinea-pig atria, was examined and the other effect to prolong the time required to arrest the spontaneous atrial contractions by addition of strophanthin-G in toxic dose, was tested, too.1) Their beta-blocking actions in the rank order of efficiency were those of carteolol, pindolol, propranolol, alprenolol, indenolol, and practolol.2) Their local anaesthetic action evaluated in cornea were ranged as those of propranolol, indenolol, and alprenolol in the order of efficiency; those of carteolol, pindolol, and practolol were very weak.3) Their local anasthetic actions evaluated in dorsal skin were ranged as those of propranolol, alprenolol, indenolol, pindolol, practolol, and carteolol.4) The effect to prevent the electrically ind uced arrhythmic contractions in the spontaneous atrial contraction was seen in propranolol, pindolol, alprenolol, and indenolol in the order of efficiency.5) The effect to prolong the time, which is required to arrest atrial spontaneous contractions by strophanthin-G in the toxic dose, was seen in propranolol, alprenolol, pindolol, indenolol, and carteolol in the order of efficiency.6) The effect of beta-blocking drug to antagonize to strophanthin-G cardiotoxicity is partly caused by its membrane stabilizing action which was tested in the experiment to examine the efficiency to prevent the arrhythmic contractions.
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治良 et al. (1987) studied this question. Beta-blockers (Alprenolol, Carteolol, Indenolol, Pindolol, Practolol, Propranolol) vs. Control (e.g., Isoproterenol alone, Strophanthin-G alone) was evaluated on Prevention of electrically induced arrhythmic contractions and prolongation of Strophanthin-G induced atrial arrest time. Propranolol, alprenolol, pindolol, and indenolol prevented electrically induced arrhythmic contractions and prolonged the time to strophanthin-G induced atrial arrest in guinea-pig tissues, effects mediated by both beta-blocking and membrane stabilizing actions.
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