We studied the mechanisms of K(+) transport in cells from isolated and perfused collecting tubule... more We studied the mechanisms of K(+) transport in cells from isolated and perfused collecting tubules and ducts from the mesonephric kidney of the toad Bufo bufo. Cells were impaled with microelectrodes across the basal cell membrane. The basolateral membrane potential (V(bl)) depolarized upon change of bath [K(+)] from 3 to 20 mmol l(-1) demonstrating a large K(+) conductance in this membrane. In collecting tubules and collecting ducts a V(bl) of -66+/-2 mV and -74+/-4 mV depolarized by 30+/-2 mV and 36+/-3 mV, respectively (N=23; 15). The K(+) channel inhibitor Ba(2+) (1 mmol l(-1)) inhibited the basolateral K(+) conductance and depolarized a V(bl) of -64+/-4 mV by 30+/-6 mV (N=8). Luminal K(+) steps (3 to 20 mmol l(-1)) demonstrated a K(+) conductance in the apical cell membrane. In collecting tubules and collecting ducts a V(bl) of -70+/-3 mV and -73+/-3 mV depolarized by 11+/-3 mV and 16+/-3 mV, respectively (N=11; 11). This conductance could also be inhibited by Ba(2+), which dep...
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2004
It is not clear how and whether terrestrial amphibians handle NaCl transport in the distal nephro... more It is not clear how and whether terrestrial amphibians handle NaCl transport in the distal nephron. Therefore, we studied ion transport in isolated perfused collecting tubules and ducts from toad, Bufo bufo, by means of microelectrodes. No qualitative difference in basolateral cell membrane potential (Vbl) was observed between tubules and ducts in response to ion substitutions, inhibitor and agonist applications.
This study deals primarily with the morphology and ultrastructure of the pronephros in the green ... more This study deals primarily with the morphology and ultrastructure of the pronephros in the green toad Bufo viridis during prometamorphosis when the pronephros and the developing mesonephros function simultaneously. Furthermore, the mesonephros was studied during pro- and postmetamorphosis with emphasis on the distal segments of the nephron. The paired kidneys consist of two cranial pronephroi immediately behind the gill region and two more caudal elongated mesonephroi. Each pronephros consists of a single convoluted tubule which opens into the coelom via three nephrostomes. This tubule is divided into three ciliated tubules, three proximal tubule branches, a common proximal tubule and a distal tubule, which in turn continues into the nephric duct. No intermediate segment is present. The length of the pronephric tubule is 12 mm, including the three branches of the ciliated tubules and proximal tubules. Primary urine is formed upon filtration from an external glomerulus, which is a convoluted capillary lined by podocytes, a specialization of the coelomic epithelium. From the coelom the filtrate is swept into the ciliated tubules. In the collecting duct system of the developing mesonephric nephron epithelial cells with conspicuous, apical osmiophilic granules appear in larvae of 9-10 mm. Heterocellularity of mixed intercalated (mitochondria rich) cells and principal cells is observed in the collecting duct system and nephric duct from a larval body length of 14 mm. As the proliferation of mitochondria-rich cells proceeds, the osmiophilic granules disappear and are completely absent from the adult amphibian mesonephros.
... (Amphibia, Anura, Bufonidae) Nadja M@bjerg,* Erik Hviid Larsenf and he Jespersen* *Department... more ... (Amphibia, Anura, Bufonidae) Nadja M@bjerg,* Erik Hviid Larsenf and he Jespersen* *Department of Cell Biology and Anatomy. Universitetsparken 15. ... DK-2100, Copenhagen 0, Denmark (Accepted for publication 24 February 1997) Abstract U~bjerg. ...
We studied the mechanisms of K(+) transport in cells from isolated and perfused collecting tubule... more We studied the mechanisms of K(+) transport in cells from isolated and perfused collecting tubules and ducts from the mesonephric kidney of the toad Bufo bufo. Cells were impaled with microelectrodes across the basal cell membrane. The basolateral membrane potential (V(bl)) depolarized upon change of bath [K(+)] from 3 to 20 mmol l(-1) demonstrating a large K(+) conductance in this membrane. In collecting tubules and collecting ducts a V(bl) of -66+/-2 mV and -74+/-4 mV depolarized by 30+/-2 mV and 36+/-3 mV, respectively (N=23; 15). The K(+) channel inhibitor Ba(2+) (1 mmol l(-1)) inhibited the basolateral K(+) conductance and depolarized a V(bl) of -64+/-4 mV by 30+/-6 mV (N=8). Luminal K(+) steps (3 to 20 mmol l(-1)) demonstrated a K(+) conductance in the apical cell membrane. In collecting tubules and collecting ducts a V(bl) of -70+/-3 mV and -73+/-3 mV depolarized by 11+/-3 mV and 16+/-3 mV, respectively (N=11; 11). This conductance could also be inhibited by Ba(2+), which dep...
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2004
It is not clear how and whether terrestrial amphibians handle NaCl transport in the distal nephro... more It is not clear how and whether terrestrial amphibians handle NaCl transport in the distal nephron. Therefore, we studied ion transport in isolated perfused collecting tubules and ducts from toad, Bufo bufo, by means of microelectrodes. No qualitative difference in basolateral cell membrane potential (Vbl) was observed between tubules and ducts in response to ion substitutions, inhibitor and agonist applications.
This study deals primarily with the morphology and ultrastructure of the pronephros in the green ... more This study deals primarily with the morphology and ultrastructure of the pronephros in the green toad Bufo viridis during prometamorphosis when the pronephros and the developing mesonephros function simultaneously. Furthermore, the mesonephros was studied during pro- and postmetamorphosis with emphasis on the distal segments of the nephron. The paired kidneys consist of two cranial pronephroi immediately behind the gill region and two more caudal elongated mesonephroi. Each pronephros consists of a single convoluted tubule which opens into the coelom via three nephrostomes. This tubule is divided into three ciliated tubules, three proximal tubule branches, a common proximal tubule and a distal tubule, which in turn continues into the nephric duct. No intermediate segment is present. The length of the pronephric tubule is 12 mm, including the three branches of the ciliated tubules and proximal tubules. Primary urine is formed upon filtration from an external glomerulus, which is a convoluted capillary lined by podocytes, a specialization of the coelomic epithelium. From the coelom the filtrate is swept into the ciliated tubules. In the collecting duct system of the developing mesonephric nephron epithelial cells with conspicuous, apical osmiophilic granules appear in larvae of 9-10 mm. Heterocellularity of mixed intercalated (mitochondria rich) cells and principal cells is observed in the collecting duct system and nephric duct from a larval body length of 14 mm. As the proliferation of mitochondria-rich cells proceeds, the osmiophilic granules disappear and are completely absent from the adult amphibian mesonephros.
... (Amphibia, Anura, Bufonidae) Nadja M@bjerg,* Erik Hviid Larsenf and he Jespersen* *Department... more ... (Amphibia, Anura, Bufonidae) Nadja M@bjerg,* Erik Hviid Larsenf and he Jespersen* *Department of Cell Biology and Anatomy. Universitetsparken 15. ... DK-2100, Copenhagen 0, Denmark (Accepted for publication 24 February 1997) Abstract U~bjerg. ...
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