Issue Archive

Hypoxic adaptation of the hearts of plateau zokor ({sl Myospalax baileyi}) and plateau pika ({sl Ochotona curzoniae})

Qi Xinzhang, Wang Xiaojun, Zhu Shihai, Rao Xinfeng, Wei Lian, Wei Dengbang

Department of Biology,Qinghai University.Xining 810016,Qinghai

Abstract

Plateau zokor (Myospalax baileyi) and plateau pika (Ochotona curzniae) are native to the Qinghai-Tibet plateau. To study their adaptive mechanisms, the ratios of heart weight to body weight (HW/BW) and right to left ventricular plus septum weights [RV/(LV+S)] were determined; the microvessel density (MVD) of cardiac muscle were measured by immunohistochemical staining; the numerical density on area (N_(A)), volume density (V_(V)), specific surface (#delta#), and surface density (S_(V)) of mitochondria were obtained by microscopy and stereology; the content of myoglobin (Mb) and lactic acid (LD), and the activity of lactate dehydrogenase (LDH) in cardiac muscle were analyzed by spectrophotometer. The results showed that the HW/BW of plateau zokor [(4.55±0.26)%] and plateau pika [(4.41±0.38)%] was significantly greater than that of Sprague-Dawley (SD) rat [(3.44±0.41)%] (P<0.05), but the RV/(LV+S) [(22.04±1.98)%, (25.53±3.41)%] was smaller than that of SD rats [(44.23±3.87)%] (P<0.05). The MVD and the N_(A) of cardiac muscle were 1 688.631±250.253 and 0.768±0.123 in SD rat, 2 002.888±367.466 and 0.868±0.159 in plateau pika and 2 990.643±389.888 and 1.012±0.133 in plateau zokor. The V_(V) of mitochondria in plateau zokor (0.272±0.045) was significantly lower than that in plateau pika (0.343±0.039) and SD rat (0.321±0.048) (P<0.05), while the #delta# of mitochondria in plateau zokor (9.409±1.238) was higher than that of plateau pika and SD rat (6.772±0.892 and 7.287±1.373) (P<0.05). The S_(V) of mitochondria in plateau pika (2.322±0.347) was not obviously different from that of plateau zokor (2.468±0.380) and SD rat (2.227±0.377), but that of plateau zokor was significantly higher than that of SD rat (P<0.05). The contents of Mb in cardiac muscle of plateau zokor [(763.33±88.73) nmol/g] and plateau pika [(765.96±28.47) nmol/g] were significantly higher than that of SD rats [(492.38±72.14) nmol/g] (P<0.05), the content of LD in plateau zokor [(0.57±0.06) mmol/L] was obviously higher than that of plateau pika [(0.45±0.06) mmol/L] and SD rat [(0.48±0.02) mmol/L] (P<0.05), and the activity of LDH in plateau zokor [(16.90±2.00) U/mL] and plateau pika [(20.55±2.46) U/mL] were significantly lower than that of SD rat [(38.26±6.78) U/mL]. The percentage of LDH-H in cardiac muscle decreased in order in plateau zokor, plateau pika and SD rat. In conclusion, plateau zokor and plateau pika adapt better to hypoxia than SD rat by increasing the SV of mitochondria, MVD and content of Mb in the cardiac muscle. However, the parameters of mitochondria in the two high-altitude animals are different possibly because of the differences of habitats and habits.

Key words: Myospalax baileyi;Ochotona curzoniae;Hypoxia;Heart

Received: 　　Accepted:

Corresponding author: 　　E-mail:

Citing This Article：

Qi Xinzhang, Wang Xiaojun, Zhu Shihai, Rao Xinfeng, Wei Lian, Wei Dengbang. Hypoxic adaptation of the hearts of plateau zokor ({sl Myospalax baileyi}) and plateau pika ({sl Ochotona curzoniae}). Acta Physiol Sin 2008; 60 (3): 348-354 (in Chinese with English abstract).