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Effects of thiopental and halothane on spontaneous contractile activity induced in isolated ventricular muscles of the rabbit
Author(s) -
Komai H.,
Redon D.,
Rusy B. F.
Publication year - 1991
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.1991.tb03313.x
Subject(s) - halothane , medicine , rabbit (cipher) , anesthesia , mathematics , statistics
To see if the known properties of thiopental of reducing Ca 2+ and K+ fluxes across the myocardial sarcolemma account for its arrhythmogenic action, we have evaluated the effect of the anesthetic on spontaneous contractile activity induced in isolated rabbit papillary muscles. Thiopental (20 mg/1) prolonged the duration of sustained automaticity induced by stimulation at 1–2 Hz in the presence of 1 μmol/I isoproterenol. Thiopental (10, 20 mg/l) shortened the delay before the onset of Ba 2+ ‐induced automaticity, which involves a decrease in a K+ current. The minimum concentration of Ba 2+ required to induce automaticity was lowered by thiopental. Whether spontaneous activities were induced by high frequency stimulation in the presence of isoproterenol or by Ba 2+ , thiopental lowered the frequency of spontaneous beats. Thus, thiopental appears to have both arrhythmogenic and antiarrhythmic actions, and the former may be unmasked when catecholamines counteract the latter by increasing Ca 2+ influx. Like thiopental, halothane (1.0%) decreased the frequency and force of Ba 2+ ‐induced automatic beats but, unlike thiopental, prolonged the delay before the onset of Ba 2+ ‐induced automaticity, indicating that halothane acts as a purely antiarrhythmic agent in this type of automaticity.