Temperature and pH effects on Ca2+ sensitivity of cardiac myofibrils: a comparison of trout with mammals.

@article{Churcott1994TemperatureAP,
  title={Temperature and pH effects on Ca2+ sensitivity of cardiac myofibrils: a comparison of trout with mammals.},
  author={Carmen S. Churcott and Christopher D Moyes and Bernard H. Bressler and Kenneth M. Baldwin and Glen F. Tibbits},
  journal={The American journal of physiology},
  year={1994},
  volume={267 1 Pt 2},
  pages={
          R62-70
        }
}
Active salmonids maintain myocardial contractility at temperatures that are cardioplegic for mammals. We postulated that myofibrillar Ca2+ sensitivity in the trout heart might 1) exhibit lower temperature dependence and/or 2) be greater over the range of physiological temperatures. Temperature-induced changes in intracellular pH may also play a role as alkalosis typically increases calcium affinity of myofibrillar adenosinetriphosphatase (ATPase). Ca2+ sensitivities of ventricular myofibrillar… 

Effects of pH and temperature on myocardial calcium-activation in Pterygoplichthys (catfish)

A possible role of the sarcoplasmic reticulum (SR) in mediating the effects of temperature and pH is suggested and the response of intact muscle preparations to changes in temperature is not likely due to temperature-dependent changes in myofilament calcium responsiveness.

Ca(2+) binding to cardiac troponin C: effects of temperature and pH on mammalian and salmonid isoforms.

A reduction in temperature lowers the Ca(2+) sensitivity of skinned cardiac myofilaments but this effect is attenuated when native cardiac troponin C (cTnC) is replaced with skeletal TnC. This

Effects of temperature and calcium availability on ventricular myocardium from rainbow trout.

The results suggest that contractile force in ventricular myocardium from Oncorhynchus mykiss is primarily regulated by sarcolemmal calcium influx and that ventricular contractility is maintained during exposure to a wide range of temperatures.

Cold acclimation increases cardiac myofilament function and ventricular pressure generation in trout

Results suggest that enhanced myofilament function, caused by modification of existing contractile proteins, is at least partially responsible for the observed increase in pressure generation after acclimation to 4°C.

Effects of temperature on intracellular Ca2+ in trout atrial myocytes.

It is suggested that temperature-dependent modulation of the AP is important for cellular Ca(2+) regulation during temperature and frequency change in rainbow trout heart.

Temperature dependence of cardiac sarcoplasmic reticulum function in rainbow trout myocytes.

It is concluded that the waveform of the AP may be critical in ensuring adequate SR Ca(2+) cycling during temperature change in rainbow trout in vivo.

Beating the cold: the functional evolution of troponin C in teleost fish.

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The high performance of turtle cardiac muscle during hypoxia does not involve a low sensitivity of the contractile system to phosphate, and the effect of increased phosphate seems to be offset by a concomitant increase in ADP.

The effects of pH and Pi on tension and Ca2+ sensitivity of ventricular myofilaments from the anoxia-tolerant painted turtle

Myofilament contractility of turtle ventricle is more sensitive to physiological levels of acidosis than to increased inorganic phosphate, which is consistent with previous studies of ectothermic vertebrates.
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