Zena Lucas A, Gargaglioni Luciane H, Bícego Kênia C
Department of Animal Morphology and Physiology, College of Agricultural and Veterinarian Sciences, São Paulo State University, Jaboticabal, São Paulo 14884-900, Brazil; National Institute of Science and Technology on Comparative Physiology (INCT- Fisiologia Comparada), Brazil.
Department of Animal Morphology and Physiology, College of Agricultural and Veterinarian Sciences, São Paulo State University, Jaboticabal, São Paulo 14884-900, Brazil; National Institute of Science and Technology on Comparative Physiology (INCT- Fisiologia Comparada), Brazil.
Comp Biochem Physiol A Mol Integr Physiol. 2015 Jan;179:81-8. doi: 10.1016/j.cbpa.2014.09.027. Epub 2014 Sep 28.
For an adequate blood supply to support metabolic demands, vertebrates regulate blood pressure to maintain sufficient perfusion to avoid ischemia and other tissue damage like edema. Using a pharmacological approach (phenylephrine and sodium nitroprusside) we investigated baroreflex sensitivity at 15, 25, and 30°C in toads Rhinella schneideri. Baroreflex sensitivity presented a high thermal dependence (Q10=1.9-4.1), and the HR-baroreflex curve was shifted up and to the right as temperature increased from 15 to 30°C. Baroreflex variables, namely, HR range, gain50 (maximal gain) and normalized gain50 increased 206, 235, and 160% from 15 to 30°C, respectively. The cardiac limb of the baroreflex response to pharmacological treatments was significantly blunted after full autonomic blockade. In addition, there was a clear baroreflex-HR response mainly to hypotension at all three temperatures tested. These findings indicate that toads present temperature dependence for cardiac limb of the barostatic response and the cardiac baroreflex response in R. schneideri is primarily hypotensive rather than hypertensive as well as crocodilians and mammals. Thus, the cardiac baroreflex compensation to changes in arterial pressure might present different patterns among amphibian species, since the previously reported bradycardic compensation to hypertension in some anurans was not observed in the toad used in the present study.
为了有足够的血液供应来支持代谢需求，脊椎动物调节血压以维持足够的灌注，避免缺血和其他组织损伤，如水肿。我们采用药理学方法（去氧肾上腺素和硝普钠）研究了15℃、25℃和30℃下蟾蜍（南美蟾蜍）的压力感受性反射敏感性。压力感受性反射敏感性呈现出较高的温度依赖性（Q10 = 1.9 - 4.1），并且随着温度从15℃升高到30℃，心率 - 压力感受性反射曲线向上和向右移动。压力感受性反射变量，即心率范围、增益50（最大增益）和标准化增益50，从15℃到30℃分别增加了206%、235%和160%。在完全自主神经阻滞后，压力感受性反射对药物治疗的心脏支反应明显减弱。此外，在所有三个测试温度下，都有明显的压力感受性反射 - 心率反应，主要是对低血压的反应。这些发现表明，蟾蜍的压力感受性反射的心脏支存在温度依赖性，并且南美蟾蜍的心脏压力感受性反射反应主要是降压而非升压，这与鳄鱼和哺乳动物相同。因此，动脉压变化时心脏压力感受性反射的代偿在两栖动物物种中可能呈现不同模式，因为在本研究中使用的蟾蜍未观察到先前报道的一些无尾两栖动物对高血压的心动过缓代偿。
