Hypothermia increases the gain of excitation-contraction coupling in guinea pig ventricular myocytes

Shutt, Robin; Howlett, Susan E.

doi:10.1152/ajpcell.00287.2008

Cited by 40 publications

(35 citation statements)

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“…Commonly, as cardiac cell contraction is in part an active energetic process, hypothermia might be expected to reduce the cardiac contractile state. However, Shutt and Howlett [6] described that paradoxical experiments with experimental animals such as guinea pig, rabbit, canine and ferret, have shown an increase in contractility and the gain of excitation-contraction coupling with cooling. They [6] also described that many studies using experimental animals had shown that cooling increases action potential duration, and slowed the rate of Na/Ca exchange in cardiac cells.…”

Section: Discussionmentioning

confidence: 99%

“…However, Shutt and Howlett [6] described that paradoxical experiments with experimental animals such as guinea pig, rabbit, canine and ferret, have shown an increase in contractility and the gain of excitation-contraction coupling with cooling. They [6] also described that many studies using experimental animals had shown that cooling increases action potential duration, and slowed the rate of Na/Ca exchange in cardiac cells. Hypothermia also increases the open probability of cardiac sarcoplasmic reticulum Ca2+ release channels, and reduces the activity of sarcoplasmic reticulum Ca2+ ATPase but increases sarcoplasmic reticulum Ca2+ load in cardiac cells [6] .…”

Section: Discussionmentioning

confidence: 99%

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Histopathological Characteristics of Human Cardiac Tissues in Accidental Hypothermia Using Conventional Staining Techniques

Wingenfeld¹,

Sakaguchi²,

Nakagawa³

2013

LSMR

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Abstract-We examined characteristics or cardiac cell damage in the myocardium obtained from individuals who died due to hypothermia or coldwater immersion. We could find four kinds of histological changes in the heart tissues obtained from hypothermia and coldwater immersion death. Although the red or orange colored cardiac cells, vacuolar cardiac cells and contraction band of the cardiac cells were observed in the heart from individuals with cardiac infarction, the frequency and intensity of the finding was remarkable in hypothermic death, and closely adhered cardiac cells were detected only in the myocardium from hypothermic or coldwater immersion death. We additionally discussed the mechanisms of development of these findings by comparing the results obtained in this examination with some reports in the literatures. Accidental hypothermia is defined as unintentional fall in core temperature under 35℃, and sever hypothermia is usually defined as under 28℃. Without through review of circumstances, the diagnosis of environmentally induced hypothermia is difficult at an autopsy, however hypothermia effects the cardiovascular, hematological, neurological, respiratory, renal, metabolic, and gastrointestinal systems [1] . Keywords-HypothermicIn this study we examined histo-pathological phenomena of the cardiac muscle obtained from individuals who died due to accidental hypothermia or immersion in cold fresh water. We found several changes occurred in the cardiac tissues in them, and are able to say that Azan staining may give the easily detected characteristics in the cardiac tissues from individuals who died due to hypothermia and/or immersion in cold water as a routine staining compared with HE staining. II MATERIAL AND METHODSWe performed 16 autopsies of hypothermic death at Department of Legal Medicine, Shiga University of Medical Science and Osaka Medical Examiner's Office during the last 4 years. The myocardium from 13 of 16 cases were examined in this study. Thirteen cases contain two old women who lived alone and died from hypothermia together with head injury after stumbling or fall from a stairs in their houses, and one child who died from abuse. The other 10 victims were found their death inside or around their houses and no remarkable injury was found on their body except the erythema on their knees in some cases. The eliminated three cases in which the victims showed prolonged postmortem interval were not suitable for the histological research. We also examined the myocardium from three cases as the comparative cases in which individuals died from drowning after immersion in a lake or canals in winter, that is, a young man was forced to go into a lake in winter, and in the last two cases young woman and man separately fell into canals with a motorcycle or a bicycle. In the last two cases, climbing traces were remained on the canal banks. Additionally we used the myocardium from traffic accidents cases with or without brain and/or cardiac injury, and cardiac infarction cases with bleeding and leukocyte i...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Histopathological Characteristics of Human Cardiac Tissues in Accidental Hypothermia Using Conventional Staining Techniques

Wingenfeld¹,

Sakaguchi²,

Nakagawa³

2013

LSMR

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“…17,18,34 Alternatively, decreasing temperature also increases RyR-Po, 17 as well as fractional and net Ca release from RyR. 17,18, 40 We contend that these 2 processes combined determine the occurrence of triggered activity. This is manifest in the biphasic nature of the mSCR slope and DAD amplitude (Figure 2B), both of which are directly related to triggered activity occurrence.…”

Section: Mechanisms Underlying the Temperature-dependent Effects Of Hmentioning

confidence: 98%

Arrhythmogenic Delayed Afterdepolarizations Are Promoted by Severe Hypothermia But Not Therapeutic Hypothermia

Fukaya

Piktel

Wan

et al. 2018

Circ J

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ryanodine receptor (RyR) dysfunction. 16-18 Given clinical observations of increased ventricular ectopy and irritability during SH, frequent triggered arrhythmias would be predicted. 10,19,20 Moreover, although repolarization abnormalities induced by hypothermia are known to promote substrates for re-entrant VF, 21 the effect of hypothermia on VF triggers is poorly understood.Despite the contrast in arrhythmia susceptibility associated with TH vs. SH, there have been very few systematic studies that have investigated the underlying arrhythmia mechanisms. Existing data on the effect of hypothermia on Ca dysregulation and triggered activity is difficult to interpret because many studies have been performed at temperatures even colder than those observed during SH (e.g., room temperature) and in varied species. 22,23 Moreover, the effect of hypothermia on cellular Ca regulation is complex, such that the net impact on susceptibility to arrhythmias is difficult to predict. Therefore, we aimed to investigate the effects of clinically relevant temperatures on Ca dysregulation and triggered arrhythmias in a single animal model at the tissue, cellular and subcellular level. We hypothesized T herapeutic hypothermia (TH) improves neurologic outcomes and survival in patients with return of spontaneous circulation (ROSC) after cardiac arrest. 1,2 Current cardiopulmonary resuscitation guidelines recommend that all comatose patients with ROSC should be cooled to have temperature maintained between 32 and 36°C for 24 h. 3-6 In addition to improving neurological outcomes, several recent experimental and clinical studies 7-9 suggest that TH decreases infarct size in acute myocardial infarction. Importantly, the incidence of lethal arrhythmias in post-resuscitated patients treated with TH is relatively low, 1,4,10 suggesting that temperatures used in clinical TH may be antiarrhythmic, although this is controversial. 11- 13 Unlike TH, severe hypothermia (SH, less than 30°C), is well known to be pro-arrhythmic. Arrhythmias in patients with accidental SH are common and include ventricular fibrillation (VF), which can be refractory to standard therapy. 14,15 Experimental studies have shown that hypothermia causes dysregulation of cellular calcium (Ca), which has been associated with intracellular Ca overload and Background: Severe hypothermia (SH) is known to be arrhythmogenic, but the effect of therapeutic hypothermia (TH) on arrhythmias is unclear. It is hypothesized that susceptibility to Ca-mediated arrhythmia triggers would be increased only by SH.

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“…Se sabe que las propiedades electrofisiológicas de las células cardíacas se ven influenciadas por la temperatura Bers 1989, Shutt andHowlett 2008]. En consecuencia, el proceso de propagación de la excitación eléctrica en el miocardio puede verse afectado, en condiciones normales o durante las arritmias, por los cambios de temperatura del tejido.…”

Section: Electrofisiología Experimental Y Temperaturaunclassified

“…Al contrario de lo que ocurre con la hipotermia, la hipertermia moderada acorta el potencial de acción e incrementa la velocidad de conducción [Tachibana et al 1999, Simmers et al 1995, Nygren et al 2003]. …”

Section: Efectos a Nivel Celularunclassified

Estudio de los efectos electrofisiológicos de la modificación local de la temperatura en un modelo experimental de corazón aislado mediante un electrodo específico de alta densidad con modulación térmica

Ibáñez¹

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Hypothermia increases the gain of excitation-contraction coupling in guinea pig ventricular myocytes

Abstract: Shutt RH, Howlett SE. Hypothermia increases the gain of excitation-contraction coupling in guinea pig ventricular myocytes.

Cited by 40 publications

References 40 publications

Histopathological Characteristics of Human Cardiac Tissues in Accidental Hypothermia Using Conventional Staining Techniques

Histopathological Characteristics of Human Cardiac Tissues in Accidental Hypothermia Using Conventional Staining Techniques

Arrhythmogenic Delayed Afterdepolarizations Are Promoted by Severe Hypothermia But Not Therapeutic Hypothermia

Estudio de los efectos electrofisiológicos de la modificación local de la temperatura en un modelo experimental de corazón aislado mediante un electrodo específico de alta densidad con modulación térmica

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