Vertebrate Renal System

Braun, Eldon J.; Dantzler, William H.

doi:10.1002/cphy.cp130108

Cited by 34 publications

(34 citation statements)

References 268 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Similarly, excess water may be excreted at the expense of salt [17,70], or it may perhaps be retained in the body to prevent acute salt loss [10]. During dehydration or salt loading, the inulin U/P ratio or creatinine U/P ratio increases in reptiles and birds, indicating that renal tubules effectively absorb water [11,70]. In contrast, significant tubular water absorption continues during water loading in desert quail; only 79% of loaded water is excreted, despite the increase in single nephron GFR and the number of filtering nephrons [10].…”

Section: Renal Responses To Osmotic Challengesmentioning

confidence: 98%

“…A larger urine flow may be required for birds to excrete uric acid and other metabolic products. In nonmammalian vertebrates, GFR is controlled intermittently [11,16]. In this context, caution is needed in interpreting the percentage of filtered water excreted/reabsorbed.…”

Section: Renal Responses To Osmotic Challengesmentioning

confidence: 98%

“…Architectural organization of the medullary cone Avian kidneys are composed of numerous medullary cones comprising grossly separated cortical and medullary regions [11,16]. The cortical reptilian-type nephrons consist of proximal tubule, intermediate segment, distal tubule, and collecting tubule and CD [9,13].…”

Section: Functional Morphology Of Avian Kidney and Urine Concentrationmentioning

confidence: 99%

See 2 more Smart Citations

Urine concentration and avian aquaporin water channels

Nishimura

2008

Pflugers Arch - Eur J Physiol

View full text Add to dashboard Cite

Although birds and mammals have evolved from primitive tetrapods and advanced divergently, both can conserve water by producing hyperosmotic urine. Unique aspects in the avian system include the presence of loopless and looped nephrons, lack of the thin ascending limb of Henle's loop, a corticomedullary osmotic gradient primarily consisting of NaCl without contribution of urea, and significant postrenal modification of final urine. The countercurrent multiplier mechanism operates between the descending and ascending limbs of Henle via recycling of a single solute (NaCl) with no water accompaniment, forming an osmotic gradient along the medullary cone. Bird kidneys and developing rat kidneys share morphological and functional characteristics. Avian kidneys express aquaporin (AQP) 1, 2, and 4 homologues that share considerable homology with mammalian counterparts, but their distribution and function may not be the same. AQP2 expression in Japanese quail (q) evolves in the collecting duct of early metanephric kidneys and continues to increase in intensity and distribution during nephrogenesis and maturation. qAQP2 mRNA and protein are increased by arginine vasotocin (avian ADH), but vasotocin-induced enhancement of cAMP production and water permeability are less marked than in mammalian kidneys. Nephrogenesis is delayed by insufficient nutrition in avian embryos and newborns and results in fewer nephrons and an impaired water balance in adults. Diabetes insipidus quail with homozygous autosomal recessive mutation and an unaffected vasotocin system have low AQP2 expression, underdeveloped medullary cones. Comparative studies will provide important insight into integrative, cellular, and molecular mechanisms of epithelial water transport and its control by humoral, neural, and hemodynamic mechanisms.

show abstract

Section: Renal Responses To Osmotic Challengesmentioning

confidence: 98%

Section: Renal Responses To Osmotic Challengesmentioning

confidence: 98%

Section: Functional Morphology Of Avian Kidney and Urine Concentrationmentioning

confidence: 99%

See 1 more Smart Citation

Urine concentration and avian aquaporin water channels

Nishimura

2008

Pflugers Arch - Eur J Physiol

View full text Add to dashboard Cite

show abstract

“…Embryologically, the head kidney and trunk kidney are derived from the pronephros and mesonephros, respectively (Romer and Parsons 1977). The head kidney is the anterior portion of the kidney and probably has no renal function (Braun and Dantzler 1997) as it consists primarily of lymphoid tissue, whereas the trunk kidney is composed of many nephrons and interstitial lymphoid tissue (Hickman and Trump 1969). Our observations have specifically dealt with the morphology and function of the trunk kidney.…”

Section: Kidney Morphologymentioning

confidence: 99%

“…Studies on the nephrons of trout, killifish, and other species have demonstrated distinct functional differences between the tubule segments (Braun and Dantzler 1997) and specific differential localization of transporters (Miyazaki et al 2002). Nishimura et al (1983) have shown that, in the distal tubule, chloride efflux (lumen to bath) is significantly higher than chloride influx (bath to lumen), suggesting the net Cl -reabsorption from the lumen to the bath and with a lumen-positive transepithelial voltage.…”

Section: Introductionmentioning

confidence: 98%

Distinct Na+/K+/2Cl- cotransporter localization in kidneys and gills of two euryhaline species, rainbow trout and killifish

et al. 2008

View full text Add to dashboard Cite

The kidney is an organ playing an important role in ion regulation in both freshwater (FW) and seawater (SW) fish. The mechanisms of ion regulation in the fish kidney are less well studied than that of their gills, especially at the level of transporter proteins. We have found striking differences in the pattern of Na(+)/K(+)/2Cl(-) cotransporter (NKCC) expression between species. In the killifish kidney, NKCC is apically localized in the distal and collecting tubules and basolaterally localized in the proximal tubules. However, in the SW killifish gill, NKCC is basolaterally co-localized with Na(+)/K(+)-ATPase, whereas in FW, NKCC immunoreactivity is primarily apical, although still colocalized within the same mitochondria-rich cell with basolateral Na(+)/K(+)-ATPase. Rainbow trout kidney has NKCC only in the apical membrane of the distal and collecting tubules in both environments, with no signal being detected in the proximal tubule. On the other hand, in the trout gill, NKCC is found basolaterally in both FW and SW environments. An important observation is that, in the gills of rainbow trout, the trailing edge of the filament possesses mostly Na(+)/K(+)-ATPase-positive but NKCC-negative mitochondria-rich cells, whereas in the region between and at the roots of the gill lamellae, most mitochondria-rich cells exhibit both Na(+)/K(+)-ATPase- and NKCC-positive immunoreactivity. These results suggest that the differential localization of transporters between the two species represents differences in function between these two euryhaline fishes with different life histories and strategies.

show abstract

Osmoregulation and Excretion

Larsen

Deaton

Onken

et al. 2014

Comprehensive Physiology

185

141

View full text Add to dashboard Cite

The article discusses advances in osmoregulation and excretion with emphasis on how multicellular animals in different osmotic environments regulate their milieu intérieur. Mechanisms of energy transformations in animal osmoregulation are dealt with in biophysical terms with respect to water and ion exchange across biological membranes and coupling of ion and water fluxes across epithelia. The discussion of functions is based on a comparative approach analyzing mechanisms that have evolved in different taxonomic groups at biochemical, cellular and tissue levels and their integration in maintaining whole body water and ion homeostasis. The focus is on recent studies of adaptations and newly discovered mechanisms of acclimatization during transitions of animals between different osmotic environments. Special attention is paid to hypotheses about the diversity of cellular organization of osmoregulatory and excretory organs such as glomerular kidneys, antennal glands, Malpighian tubules and insect gut, gills, integument and intestine, with accounts on experimental approaches and methods applied in the studies. It is demonstrated how knowledge in these areas of comparative physiology has expanded considerably during the last two decades, bridging seminal classical works with studies based on new approaches at all levels of anatomical and functional organization. A number of as yet partially unanswered questions are emphasized, some of which are about how water and solute exchange mechanisms at lower levels are integrated for regulating whole body extracellular water volume and ion homeostasis of animals in their natural habitats. © 2014 American Physiological Society.

show abstract

Vertebrate Renal System

Abstract: The sections in this article are: External and Internal Gross Morphology of Vertebrate Kidneys Fishes Amphibians Reptiles Birds Mammals Glomerular Ultrafiltration Glomerular Filtration Rate: Stability and Variability … Show more

Cited by 34 publications

References 268 publications

Urine concentration and avian aquaporin water channels

Urine concentration and avian aquaporin water channels

Distinct Na+/K+/2Cl- cotransporter localization in kidneys and gills of two euryhaline species, rainbow trout and killifish

Osmoregulation and Excretion

Contact Info

Product

Resources

About