A model for passive urea reabsorption in the elasmobranch kidney

Morphological and functional characteristics of the kidney of cartilaginous fishes: with special reference to urea reabsorption

“…Because the facilitative UT is localized on both apical and basolateral membranes of epithelial cells, urea transport in the collecting tubule could be attributed to passive permeation. This hypothesis is supported by the previous anatomical studies (13,22). Based on the anatomical relationships among nephron segments examined in spiny dogfish and little skate, Boylan and colleagues (13,22) proposed a model for passive urea reabsorption in the elasmobranch kidney.In their model, urea diffuses from the collecting tubule into the interstitial fluid around it, lowering the urea concentration of the final urine.…”

“…This hypothesis is supported by the previous anatomical studies (13,22). Based on the anatomical relationships among nephron segments examined in spiny dogfish and little skate, Boylan and colleagues (13,22) proposed a model for passive urea reabsorption in the elasmobranch kidney.In their model, urea diffuses from the collecting tubule into the interstitial fluid around it, lowering the urea concentration of the final urine. The importance of the collecting tubule for urea reabsorption is also supported by the results of renal micropuncture and microdissection studies (22,98,99,107).…”

Morphological and functional characteristics of the kidney of cartilaginous fishes: with special reference to urea reabsorption

“…Because the facilitative UT is localized on both apical and basolateral membranes of epithelial cells, urea transport in the collecting tubule could be attributed to passive permeation. This hypothesis is supported by the previous anatomical studies (13,22). Based on the anatomical relationships among nephron segments examined in spiny dogfish and little skate, Boylan and colleagues (13,22) proposed a model for passive urea reabsorption in the elasmobranch kidney.In their model, urea diffuses from the collecting tubule into the interstitial fluid around it, lowering the urea concentration of the final urine.…”

“…This hypothesis is supported by the previous anatomical studies (13,22). Based on the anatomical relationships among nephron segments examined in spiny dogfish and little skate, Boylan and colleagues (13,22) proposed a model for passive urea reabsorption in the elasmobranch kidney.In their model, urea diffuses from the collecting tubule into the interstitial fluid around it, lowering the urea concentration of the final urine. The importance of the collecting tubule for urea reabsorption is also supported by the results of renal micropuncture and microdissection studies (22,98,99,107).…”

The fine structure of the elasmobranch renal tubule: Intermediate, distal, and collecting duct segments of the little skate

“…It would appear from those studies that urinary dilution occurs in Di-11, although the morphology of these cells as reported here is not typical of sodiumabsorbing epithelia (Berridge and Oschman, 1972). Furthermore, tubular micropuncture studies have shown that the collecting duct, which lies outside the tubular bundle, is not the major site of tubular urea reabsorption (Deetjen, 1972;Stolte et al, 19771, adding credence to the hypothesis that the countercurrent system is responsible for urea reabsorption (Boylan, 1972;Lacy and Reale, 1985a;Lacy et al, 1985).…”

Molecular and functional characterization of a urea transporter from the kidney of the Atlantic stingray

“…The countercurrent arrangement of the marine elasmobranch nephron (23) supports the role of passive mechanisms in renal urea reabsorption (3,13). A phloretin-sensitive, facilitated urea transporter has been cloned from the kidney of the spiny dogfish shark, a marginally euryhaline elasmobranch (39).…”

Morphological and functional characteristics of the kidney of cartilaginous fishes: with special reference to urea reabsorption

“…Because the facilitative UT is localized on both apical and basolateral membranes of epithelial cells, urea transport in the collecting tubule could be attributed to passive permeation. This hypothesis is supported by the previous anatomical studies (13,22). Based on the anatomical relationships among nephron segments examined in spiny dogfish and little skate, Boylan and colleagues (13,22) proposed a model for passive urea reabsorption in the elasmobranch kidney.In their model, urea diffuses from the collecting tubule into the interstitial fluid around it, lowering the urea concentration of the final urine.…”

“…This hypothesis is supported by the previous anatomical studies (13,22). Based on the anatomical relationships among nephron segments examined in spiny dogfish and little skate, Boylan and colleagues (13,22) proposed a model for passive urea reabsorption in the elasmobranch kidney.In their model, urea diffuses from the collecting tubule into the interstitial fluid around it, lowering the urea concentration of the final urine. The importance of the collecting tubule for urea reabsorption is also supported by the results of renal micropuncture and microdissection studies (22,98,99,107).…”

The fine structure of the elasmobranch renal tubule: Intermediate, distal, and collecting duct segments of the little skate

“…It would appear from those studies that urinary dilution occurs in Di-11, although the morphology of these cells as reported here is not typical of sodiumabsorbing epithelia (Berridge and Oschman, 1972). Furthermore, tubular micropuncture studies have shown that the collecting duct, which lies outside the tubular bundle, is not the major site of tubular urea reabsorption (Deetjen, 1972;Stolte et al, 19771, adding credence to the hypothesis that the countercurrent system is responsible for urea reabsorption (Boylan, 1972;Lacy and Reale, 1985a;Lacy et al, 1985).…”

Molecular and functional characterization of a urea transporter from the kidney of the Atlantic stingray

“…The countercurrent arrangement of the marine elasmobranch nephron (23) supports the role of passive mechanisms in renal urea reabsorption (3,13). A phloretin-sensitive, facilitated urea transporter has been cloned from the kidney of the spiny dogfish shark, a marginally euryhaline elasmobranch (39).…”

Morphological and functional characteristics of the kidney of cartilaginous fishes: with special reference to urea reabsorption

“…Because the facilitative UT is localized on both apical and basolateral membranes of epithelial cells, urea transport in the collecting tubule could be attributed to passive permeation. This hypothesis is supported by the previous anatomical studies (13,22). Based on the anatomical relationships among nephron segments examined in spiny dogfish and little skate, Boylan and colleagues (13,22) proposed a model for passive urea reabsorption in the elasmobranch kidney.In their model, urea diffuses from the collecting tubule into the interstitial fluid around it, lowering the urea concentration of the final urine.…”

“…This hypothesis is supported by the previous anatomical studies (13,22). Based on the anatomical relationships among nephron segments examined in spiny dogfish and little skate, Boylan and colleagues (13,22) proposed a model for passive urea reabsorption in the elasmobranch kidney.In their model, urea diffuses from the collecting tubule into the interstitial fluid around it, lowering the urea concentration of the final urine. The importance of the collecting tubule for urea reabsorption is also supported by the results of renal micropuncture and microdissection studies (22,98,99,107).…”

The fine structure of the elasmobranch renal tubule: Intermediate, distal, and collecting duct segments of the little skate

“…It would appear from those studies that urinary dilution occurs in Di-11, although the morphology of these cells as reported here is not typical of sodiumabsorbing epithelia (Berridge and Oschman, 1972). Furthermore, tubular micropuncture studies have shown that the collecting duct, which lies outside the tubular bundle, is not the major site of tubular urea reabsorption (Deetjen, 1972;Stolte et al, 19771, adding credence to the hypothesis that the countercurrent system is responsible for urea reabsorption (Boylan, 1972;Lacy and Reale, 1985a;Lacy et al, 1985).…”

Molecular and functional characterization of a urea transporter from the kidney of the Atlantic stingray

“…The countercurrent arrangement of the marine elasmobranch nephron (23) supports the role of passive mechanisms in renal urea reabsorption (3,13). A phloretin-sensitive, facilitated urea transporter has been cloned from the kidney of the spiny dogfish shark, a marginally euryhaline elasmobranch (39).…”