Effects of change in frequency of stimulation on myocardial depression produced by thiamylal and halothane.

Iwatsuki, Naofumi; Iwatsuki, Kazuhiko

doi:10.1620/tjem.117.119

Cited by 3 publications

(2 citation statements)

References 8 publications

(4 reference statements)

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“…In the light of other work (8) concerning the importance of transsarcolemmally derived Ca2+ to force production during rested-state contractions, it can be inferred from our observation that halothane exerts an important action on the cell membrane to inhibit Ca2+ influx. This notion is supported by the work of Hauswirth (1) which shows that halothane shortens the cardiac action potential duration and by the work Iwatzuki and Iwatzuki (15) have shown that increasing stimulation frequency does not reverse the negative inotropic effect of halothane. If the effect of halothane is limited to a competitive inhibition of transsarcolemma1 Ca2+ influx, one might expect paired-pulse stimulation at an optimal frequency to overcome the negative inotropic effect of the anesthetic by maximizing the transsarcolemmal Ca2+ influx.…”

Section: Discussionmentioning

confidence: 78%

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Effect of Halothane on Rested-State and Potentiated-State Contractions in Rabbit Papillary Muscle

Komai¹,

Rusy²

1982

Anesthesia & Analgesia

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Effect of halothane on rested-state and potentiated-state contractions in rabbit papillary muscle: relationship to negative inotropic action. Anesth Analg 1982;61:403-9.The effect of halothane on the availability of different sources of activator calcium for myocardial contraction was evaluated in relationship to the negative inotropic effect of the anesthetic. This was studied in rabbit papillary muscle under various stimulation conditions that are known to vary the importance of one or another of two sources of Ca'+ for production of contraction. The rested-state contraction is known to depend primarily on the transsarcolemmal influx of Caz+ for its activation whereas the potentiated-state contraction is dependent largely on Ca'+ released from intracellular stores. In the presence of 0.6% halothane (gas phase) the rested-state and potentiated-state contractions were depressed (mean & SEM) 38% & 5% (n = 15) and 32% f 3% (n = 7), respectively (no statistically significant difference). Halothane accelerated the decay of the potentiated state, indicating that it stimulates the loss of Ca2+ from internal stores. Halothane also acted to slow the time course of force increase following restimulation of rested muscles, indicating that it inhibits the filling of internal stores. These observations suggest that the negative inotropic effect of halothane is caused by a combination of quantitatively similar effects of the anesthetic on the transsarcolemmal and intracellular sources of activator Ca".

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Section: Discussionmentioning

confidence: 78%

“…The time to reach a steady contractile state following an increase in the stimulation frequency (staircase) is known to be prolonged in the presence of halothane (15). In this regard, halothane resembles caffeine, which prolongs the time to reach a steady-state contraction following a change in Stimulation frequency (24).…”

Section: Discussionmentioning

confidence: 99%

Effect of Halothane on Rested-State and Potentiated-State Contractions in Rabbit Papillary Muscle

Komai¹,

Rusy²

1982

Anesthesia & Analgesia

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Effect of Thiamylal on the Sensitivity of Glycerinated Cardiac Fibres to Calcium

Iwatsuki

Yasuda

Iwatsuki

1978

British Journal of Anaesthesia

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Clarification of the mechanisms of the myocardial depression produced by thiamylal was sought by studying the effect of thiamylal upon the sensitivity of contractile proteins to calcium (Ca2+), by using glycerinated muscle fibres from the canine right ventricle. The dose--response relationship between the concentration of Ca2+ and the force of contraction of the glycerinated cardiac muscle fibres was not shifted from the control curve by the administration of thiamylal 67 microgram ml-1. This result suggests that the changes in the sensitivity of contractile proteins to Ca2+ are not responsible for the depression of myocardial performance produced by thiamylal.

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Effects of change in concentration of calcium on myocardial contractility depressed by thiamylal and halothane.

Iwatsuki

1976

Tohoku J. Exp. Med.

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Effects of change in frequency of stimulation on myocardial depression produced by thiamylal and halothane.

Cited by 3 publications

References 8 publications

Effect of Halothane on Rested-State and Potentiated-State Contractions in Rabbit Papillary Muscle

Effect of Halothane on Rested-State and Potentiated-State Contractions in Rabbit Papillary Muscle

Effect of Thiamylal on the Sensitivity of Glycerinated Cardiac Fibres to Calcium

Effects of change in concentration of calcium on myocardial contractility depressed by thiamylal and halothane.

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