The effect of temperature on the rate‐dependent decrease of the rat ventricular calcium current

McMorn, Stephen O.; Harrison, SM; Boyett, Mark R.

doi:10.1113/expphysiol.1998.sp004091

Cited by 6 publications

(11 citation statements)

References 18 publications

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“…Specifically, peak I Ca,L at 22°C was 8.31 pA/pF compared with 15.05 pA/pF at 38°C, whereas time taken for 50% 50% I Ca,L inactivation (RT 50, I ) decreased from 10.75 ms at 22°C to 2.95 ms 38°C (inset in Figure 10A). These indices are in general agreement with measured voltage clamp data [32,33] obtained from rat ventricular trabeculae. …”

Section: Resultssupporting

confidence: 89%

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Multiphysics model of a rat ventricular myocyte: A voltage-clamp study

Krishna

Valderrábano

Palade

et al. 2012

Theor Biol Med Model

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BackgroundThe objective of this study is to develop a comprehensive model of the electromechanical behavior of the rat ventricular myocyte to investigate the various factors influencing its contractile response.MethodsHere, we couple a model of Ca2 + dynamics described in our previous work, with a well-known model of contractile mechanics developed by Rice, Wang, Bers and de Tombe to develop a composite multiphysics model of excitation-contraction coupling. This comprehensive cell model is studied under voltage clamp (VC) conditions, since it allows to focus our study on the elaborate Ca2 + signaling system that controls the contractile mechanism.ResultsWe examine the role of various factors influencing cellular contractile response. In particular, direct factors such as the amount of activator Ca2 + available to trigger contraction and the type of mechanical load applied (resulting in isosarcometric, isometric or unloaded contraction) are investigated. We also study the impact of temperature (22 to 38°C) on myofilament contractile response. The critical role of myofilament Ca2 + sensitivity in modulating developed force is likewise studied, as is the indirect coupling of intracellular contractile mechanism with the plasma membrane via the Na + /Ca2 + exchanger (NCX). Finally, we demonstrate a key linear relationship between the rate of contraction and relaxation, which is shown here to be intrinsically coupled over the full range of physiological perturbations.ConclusionsExtensive testing of the composite model elucidates the importance of various direct and indirect modulatory influences on cellular twitch response with wide agreement with measured data on all accounts. Thus, the model provides mechanistic insights into whole-cell responses to a wide variety of testing approaches used in studies of cardiac myofilament contractility that have appeared in the literature over the past several decades.

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Section: Resultssupporting

confidence: 89%

“…One very significant effect of temperature on whole-cell I Ca,L is the pronounced increase in its rate of decline with an increase in temperature [31,32]. Thus, with an increase from room to body temperature, peak inward trigger current increases but the waveform becomes much narrower.…”

Section: Resultsmentioning

confidence: 99%

Multiphysics model of a rat ventricular myocyte: A voltage-clamp study

Krishna

Valderrábano

Palade

et al. 2012

Theor Biol Med Model

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“…The present study, which administered discrete doses by instillation rather than inhalation, was able to control for the rst potential confounder, but not the latter. Enzyme kinetics and production of biochemical intermediates are mediated in part by T co (McMorn et al, 1998;Puntarulo & Cederbaum, 1989). If the temperature of the alveoli decreases, the quantit y of radicals or intermediates generated upon contact of the particles with the surfactant could be reduced.…”

Section: Discussionmentioning

confidence: 99%

Cardiac and Thermoregulatory Toxicity of Residual Oil Fly Ash in Cardiopulmonary-Compromised Rats

Campen¹,

Costa²,

Watkinson³

2000

Inhalation Toxicology

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Recent epidemiological studies have reported a positive association between levels of ambient particulate matter ( PM) and daily morbidity and mortality due to respiratory or cardiovascular causes; however, toxicological evidence supporting these ndings is limited. The present study compared cardiac and thermoregulatory responses to intratracheal instillations of residual oil y ash ( ROFA) in normal and cardiopulmonary-compromised male Sprague-Dawley rats. Animals ( n = 64) were implanted with radiotelemetry transmitters capable of continuously monitoring heart rate, core body temperature, and electrocardiographic waveforms. Comparisons of ROFA toxicity were conducted between ( 1) healthy rats and rats with cardiopulmonary stress or disease, including ( 2) rats exposed to an ambient temperature of 10°C, ( 3) rats preexposed to ozone to induce pulmonary in ammation, and ( 4) rats pretreated with monocrotaline ( MCT) to induce pulmonary hypertension and vasculitis. Animals from each regimen were instilled with 1 of 4 doses of ROFA ( 0, 0.25, 1.0, 2.5 mg) , and telemetry data were acquired for 96 h following ROFA instillation. Doserelated hypothermia and bradycardia were observed in healthy animals following exposure to ROFA; the magnitude and duration of these responses were potentiated in all compromised models. Delayed hypothermic and bradycardic responses occurred in healthy animals receiving 2.5 mg ROFA up to 48 h following instillation. These delayed responses were exacerbated in the MCT-and 10°C-exposure models, but attenuated in the O 3 -preexposed group. Additional observed effects of ROFA included induction of cardiac arrhythmiasThe authors thank Dr. Urmila P. Kodavanti, Julie P. Nolan, and James A. Raub for their thoughtful reviews of this article. Further gratitude is extended to

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“…Nobile et al, 1990;Takahashi et al, 1991) whereas other Ca 2+ channels have kinetics with Q 10 values of about 5 (e.g. Byerly et al, 1984;Delbono & Stefani, 1993;McMorn et al, 1998).…”

Section: Discussionmentioning

confidence: 97%

Impulse conduction in the jellyfish Aglantha digitale

Meech¹

2004

Hydrobiologia

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In the jellyfish Aglantha digitale two forms of swimming arise from two separate propagating axonal impulses: a fast, overshooting action potential that depends on TTX-resistant Na + channels, and a lowamplitude spike that depends on T-type Ca 2+ channels. While the Na + action potential is propagated simply and without distortion, the shape of the Ca 2+ spike depends on the past history of the axon; it is processed as well as propagated. Patch-and voltage-clamp experiments show how three classes of K + channels contribute to this apparently unique system. A dual Na + /Ca 2+ impulse mechanism may increase the bandwidth of an axonal line of communication but it also places restrictions on the form of the synaptic input needed for spike initiation.

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The effect of temperature on the rate‐dependent decrease of the rat ventricular calcium current

Cited by 6 publications

References 18 publications

Multiphysics model of a rat ventricular myocyte: A voltage-clamp study

Multiphysics model of a rat ventricular myocyte: A voltage-clamp study

Cardiac and Thermoregulatory Toxicity of Residual Oil Fly Ash in Cardiopulmonary-Compromised Rats

Impulse conduction in the jellyfish Aglantha digitale

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