Department of Animal Morphology and Physiology, Sao Paulo State University - UNESP FCAV at Jaboticabal, SP, Brazil.
Comp Biochem Physiol A Mol Integr Physiol. 2012 Jul;162(3):281-7. doi: 10.1016/j.cbpa.2012.03.020. Epub 2012 Apr 3.
Anuran amphibians are known to exhibit an intermittent pattern of pulmonary ventilation and to exhibit an increased ventilatory response to hypoxia and hypercarbia. However, only a few species have been studied to date. The aquatic frog Pipa carvalhoi inhabits lakes, ponds and marshes that are rich in nutrients but low in O(2). There are no studies of the respiratory pattern of this species and its ventilation during hypoxia or hypercarbia. Accordingly, the aim of the present study was to characterize the breathing pattern and the ventilatory response to aquatic and aerial hypoxia and hypercarbia in this species. With this purpose, pulmonary ventilation (V(I)) was directly measured by the pneumotachograph method during normocapnic normoxia to determine the basal respiratory pattern and during aerial and aquatic hypercarbia (5% CO(2)) and hypoxia (5% O(2)). Our data demonstrate that P. carvalhoi exhibits a periodic breathing pattern composed of single events (single breaths) of pulmonary ventilation separated by periods of apnea. The animals had an enhanced V(I) during aerial hypoxia, but not during aquatic hypoxia. This increase was strictly the result of an increase in the breathing frequency. A pronounced increase in V(I) was observed if the animals were simultaneously exposed to aerial and aquatic hypercarbia, whereas small or no ventilatory responses were observed during separately administered aerial or aquatic hypercarbia. P. carvalhoi primarily inhabits an aquatic environment. Nevertheless, it does not respond to low O(2) levels in water, although it does so in air. The observed ventilatory responses to hypercarbia may indicate that this species is similar to other anurans in possessing central chemoreceptors.
蛙类被认为表现出间歇性的肺通气模式，并对低氧和高碳酸血症表现出增强的通气反应。然而，迄今为止，只有少数几种物种得到了研究。水生蛙类 Pipa carvalhoi 栖息在富含有机物但低氧的湖泊、池塘和沼泽中。目前还没有关于该物种呼吸模式及其在低氧或高碳酸血症下通气的研究。因此，本研究的目的是描述该物种的呼吸模式及其对水生和大气低氧和高碳酸血症的通气反应。为此，我们通过呼吸描记法直接测量了肺通气量（V[I]），以确定在常氧常二氧化碳下的基础呼吸模式，并在大气和水的高碳酸血症（5% CO[2]）和低氧（5% O[2]）下进行通气。我们的数据表明，P. carvalhoi 表现出周期性的呼吸模式，由肺通气的单个事件（单次呼吸）组成，这些事件由呼吸暂停期隔开。动物在大气低氧时表现出增强的 V[I]，但在水低氧时没有。这种增加严格是呼吸频率增加的结果。如果同时暴露于大气和水的高碳酸血症下，动物的 V[I]会显著增加，而单独给予大气或水的高碳酸血症时，V[I]的反应较小或没有。P. carvalhoi 主要栖息在水生环境中。然而，它对水中的低氧水平没有反应，尽管它在空气中有反应。对高碳酸血症观察到的通气反应可能表明该物种与其他蛙类一样具有中枢化学感受器。
