A nectar-feeding mammal avoids body fluid disturbances by varying renal function. Am J Physiol Renal Physiol 295: F1855-F1863, 2008. First published October 22, 2008; doi:10.1152/ajprenal.90349.2008.-To maintain water and electrolyte balance, nectar-feeding vertebrates oscillate between two extremes: avoiding overhydration when feeding and preventing dehydration during fasts. Several studies have examined how birds resolve this osmoregulatory dilemma, but no data are available for nectar-feeding mammals. In this article, we 1) estimated the ability of Pallas's long-tongued bats (Glossophaga soricina; Phyllostomidae) to dilute and concentrate urine and 2) examined how water intake affected the processes that these bats use to maintain water balance. Total urine osmolality in water- and salt-loaded bats ranged between 31 +- 37 mosmol/kgH2O (n = 6) and 578 +- 56 mosmol/kgHaO (n = 2), respectively. Fractional water absorption in the gastrointestinal tract was not affected by water intake rate. As a result,water flux, body water turnover, and renal water load all increased with increasing water intake. Despite these relationships, glomerular nitration rate (GFR) was not responsive to water loading. To eliminate excess water, Pallas's long-tongued bats increased water excretion rate by reducing fractional renal water reabsorption. We also found that rates of total evaporative water loss increased with increasing water intake. During their natural daytime fast, mean GFR in Pallas's long-tongued bats was 0.37 ml/h in = 10). This is ~90% lower than the GFR we measured in fed bats. Our findings 1) suggest that Pallas's long-tongued bats do not have an exceptional urine-diluting or -concentrating ability and 2) demonstrate that the bats eliminate excess ingested water by reducing renal water reabsorption and limit urinary water loss during fasting periods by reducing GFR
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机译：以花蜜为食的哺乳动物通过改变肾功能避免体液紊乱。 Am J Physiol Renal Physiol 295：F1855-F1863，2008年。2008年10月22日首次发布。 doi：10.1152 / ajprenal.90349.2008.-为维持水和电解质的平衡，以花蜜喂养的脊椎动物在两个极端之间振荡：避免喂食时过度水化和防止斋戒时脱水。几项研究已经研究了鸟类如何解决这种渗透调节难题，但尚无有关以花蜜为食的哺乳动物的数据。在本文中，我们1）评估了帕拉斯长舌蝙蝠（Glossophaga soricina; Phyllostomidae）稀释和浓缩尿液的能力，以及2）检查了摄水量如何影响这些蝙蝠维持水平衡的过程。在装有水和盐的蝙蝠中，总尿渗透压在31±37 mosmol / kgH2O（n = 6）和578±56 mosmol / kgHaO（n = 2）之间。胃肠道的部分吸水率不受吸水率的影响。结果，水的通量，人体水的周转量和肾脏的水负荷都随着饮水量的增加而增加。尽管有这些关系，肾小球硝化率（GFR）对水负荷没有反应。为了消除多余的水，Pallas的长舌蝙蝠通过减少部分肾脏对水的重吸收来提高水的排泄率。我们还发现，随着水摄入量的增加，蒸发水的总损失率也随之增加。在自然白天禁食期间，帕拉斯长舌蝙蝠的平均GFR为0.37 ml / h in = 10）。这比我们在饲喂蝙蝠中测得的GFR低约90％。我们的发现1）表明Pallas的长long蝙蝠没有特殊的尿液稀释或浓缩能力，并且2）表明蝙蝠通过减少肾脏对水的重吸收来消除过量的摄入水，并通过降低GFR来限制禁食期间的尿失水
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