At high temperatures, ventricular beating rate collapses and depresses cardiac output in fish. The role of sarco(endo)plasmic reticulum Ca 2+ -ATPase (SERCA) in thermal tolerance of ventricular function was examined in brown trout ( Salmo trutta ) by measuring heart SERCA and comparing it to that of the dorsolateral myotomal muscle. Activity of SERCA was measured from crude homogenates of cold-acclimated (+ 3 °C, c.a.) and warm-acclimated (+ 13 °C, w.a.) brown trout as cyclopiazonic acid (20 µM) sensitive Ca 2+ -ATPase between + 3 and + 33 °C. Activity of the heart SERCA was significantly higher in c.a. than w.a. trout and increased strongly between + 3 and + 23 °C with linear Arrhenius plots but started to plateau between + 23 and + 33 °C in both acclimation groups. The rate of thermal inactivation of the heart SERCA at + 35 °C was similar in c.a. and w.a. fish. Activity of the muscle SERCA was less temperature dependent and more heat resistant than that of the heart SERCA and showed linear Arrhenius plots between + 3 and + 33 °C in both c.a. and w.a. fish. SERCA activity of the c.a. muscle was slightly higher than that of w.a. muscle. The rate of thermal inactivation at + 40 °C was similar for both c.a. and w.a. muscle SERCA at + 40 °C. Although the heart SERCA is more sensitive to high temperatures than the muscle SERCA, it is unlikely to be a limiting factor for heart rate, because its heat tolerance, unlike that of the ventricular beating rate, was not changed by temperature acclimation.

中文翻译：

---

急性变暖对热驯化褐鳟 (Salmo trutta) 心脏和肌瘤 (内) 质网 ATP 酶 (SERCA) 的影响

在高温下，心室搏动率下降并抑制鱼的心输出量。在褐鳟 (Salmo trutta) 中，通过测量心脏 SERCA 并将其与背外侧肌断层肌的 SERCA 进行比较，研究了 sarco(endo)plasmic reticulum Ca 2+ -ATPase (SERCA) 在心室功能耐热性中的作用。SERCA 的活性是从冷驯化 (+ 3 °C, ca) 和暖驯化 (+ 13 °C, wa) 褐鳟的粗匀浆中测量的，作为环吡唑酸 (20 µM) 敏感的 Ca 2+ -ATPase 在 + 3 之间和 + 33 °C。ca 中心脏 SERCA 的活性显着高于 wa 鳟鱼，并且在 + 3 和 + 23 °C 之间强烈增加，线性 Arrhenius 图，但在两个适应组中开始在 + 23 和 + 33 °C 之间稳定。+ 35 °C 时心脏 SERCA 的热失活率与 ca 相似 和鱼。与心脏 SERCA 相比，肌肉 SERCA 的活动对温度的依赖性更小，耐热性更强，并且在 ca 和 wa 鱼中都显示出 + 3 和 + 33 °C 之间的线性 Arrhenius 图。ca肌的SERCA活性略高于wa肌。在 + 40 °C 下，ca 和 wa 肌肉 SERCA 在 + 40 °C 下的热失活率相似。虽然心脏 SERCA 比肌肉 SERCA 对高温更敏感，但它不太可能成为心率的限制因素，因为它的耐热性与心室跳动率不同，不会因温度适应而改变。和鱼。ca肌的SERCA活性略高于wa肌。在 + 40 °C 下，ca 和 wa 肌肉 SERCA 在 + 40 °C 下的热失活率相似。虽然心脏 SERCA 比肌肉 SERCA 对高温更敏感，但它不太可能成为心率的限制因素，因为它的耐热性与心室跳动率不同，不会因温度适应而改变。和鱼。ca肌的SERCA活性略高于wa肌。在 + 40 °C 下，ca 和 wa 肌肉 SERCA 在 + 40 °C 下的热失活率相似。虽然心脏 SERCA 比肌肉 SERCA 对高温更敏感，但它不太可能成为心率的限制因素，因为它的耐热性与心室跳动率不同，不会因温度适应而改变。