Two modes of Na extrusion in cells from guinea pig kidney cortex slices

1970 ◽  
Vol 316 (1) ◽  
pp. 1-25 ◽  
Author(s):  
G. Whittembury ◽  
F. Proverbio
Keyword(s):  
Guinea Pig ◽  
Kidney Cortex ◽  
Pig Kidney ◽  
Cortex Slices ◽  
Kidney Cortex Slices ◽  
In Cells

scholarly journals Analyse der strahleninduzierten Elektrolytveränderungen in Nierenschnitten

1960 ◽  
Vol 15 (10) ◽  
pp. 671-675
Author(s):  
H. Breuer ◽  
H. K. Parchwitz
Keyword(s):  
Oxygen Uptake ◽  
Guinea Pig ◽  
Transport Mechanism ◽  
Kidney Cortex ◽  
Concentration Gradients ◽  
Tissue Slices ◽  
Pig Kidney ◽  
X Irradiation ◽  
Cortex Slices ◽  
Kidney Cortex Slices

The effect of X-irradiation (14 000 r-58 000 r) on the movements of potassium and sodium in guinea pig kidney cortex slices after incubation under various conditions has been investigated. In addition, the oxygen uptake of the tissue slices has been measured.The concentration gradients of potassium and sodium between slices and medium were reduced after X-irradiation. However, this reduction was only found when the slices were incubated at 37°C. At lower temperatures no effect of X-irradiation was observed. The oxygen uptake of the kidney cortex slices remained unaffected by X-irradiation.The experiments described in the present paper suggest that X-irradiation acts on the ion transport mechanism itself rather than on energy supplying processes.

scholarly journals Sodium Extrusion and Potassium Uptake in Guinea Pig Kidney Cortex Slices

1965 ◽  
Vol 48 (4) ◽  
pp. 699-717 ◽  
Author(s):  
Guillermo Whittembury
Keyword(s):  
Guinea Pig ◽  
Potential Gradient ◽  
Electrochemical Potential ◽  
Kidney Cortex ◽  
K Uptake ◽  
Pig Kidney ◽  
Cortex Slices ◽  
Sodium Extrusion ◽  
Kidney Cortex Slices ◽  
Bathing Fluid

Slices from the cortex corticis of the guinea pig kidney were immersed in a chilled solution without K and then reimmersed in warmer solutions. The Na and K concentrations and the membrane potential Vm were then studied as a function of the Na and K concentrations of the reimmersion fluid. It was found that Na is extruded from the cells against a large electrochemical potential gradient. Q10 for net Na outflux was ∼2.5. At bath K concentrations larger than 8 mM the behavior of K was largely passive. At the outset of reimmersion (Vm > EK) K influx seemed secondary to Na extrusion. Na extrusion would promote K entrance, being limited and requiring the presence of K in the bathing fluid. At bath K concentrations below 8 mM, K influx was up an electrochemical potential gradient. Thus a parallel active K uptake is apparent. Q10 for net K influx was ∼2.0. Dinitrophenol inhibited net Na outflux and net K influx, Q10 became <1.1 for both fluxes. The ratio between these fluxes varied. Thus at the outset of reimmersion the net Na outflux to net K influx ratio was >1. After 8 minutes it was <1.

scholarly journals Fate of glutamate carbon and nitrogen in isolated guinea-pig kidney-cortex tubules. Evidence for involvement of glutamate dehydrogenase in glutamine sythesis from glutamate

1980 ◽  
Vol 188 (3) ◽  
pp. 873-880 ◽  
Author(s):  
G Baverel ◽  
C Genoux ◽  
M Forissier ◽  
M Pellet
Keyword(s):  
Guinea Pig ◽  
Glutamate Dehydrogenase ◽  
Carbon Skeleton ◽  
Kidney Cortex ◽  
Glutamate Metabolism ◽  
Carbon And Nitrogen ◽  
Pig Kidney ◽  
Glutamate Concentration ◽  
Rate Limiting Step

1. The pathways and the fate of glutamate carbon and nitrogen were investigated in isolated guinea-pig kidney-cortex tubules. 2. At low glutamate concentration (1 mM), the glutamate carbon skeleton was either completely oxidized or converted into glutamine. At high glutamate concentration (5 mM), glucose, lactate and alanine were additional products of glutamate metabolism. 3. At neither concentration of glutamate was there accumulation of ammonia. 4. Nitrogen-balance calculations and the release of 14CO2 from L-[1-14C]glutamate (which gives an estimation of the flux of glutamate carbon skeleton through alpha-oxoglutarate dehydrogenase) clearly indicated that, despite the absence of ammonia accumulation, glutamate metabolism was initiated by the action of glutamate dehydrogenase and not by transamination reactions as suggested by Klahr, Schoolwerth & Bourgoignie [(1972) Am. J. Physiol. 222, 813-820] and Preuss [(1972) Am. J. Physiol. 222, 1395-1397]. Additional evidence for this was obtained by the use of (i) amino-oxyacetate, an inhibitor of transaminases, which did not decrease glutamate removal, or (ii) L-methionine DL-sulphoximine, an inhibitor of glutamine synthetase, which caused an accumulation of ammonia from glutamate. 5. Addition of NH4Cl plus glutamate caused an increase in both glutamate removal and glutamine synthesis, demonstrating that the supply of ammonia via glutamate dehydrogenase is the rate-limiting step in glutamine formation from glutamate. NH4Cl also inhibited the flux of glutamate through glutamate dehydrogenase and the formation of glucose, alanine and lactate. 6. The activities of enzymes possibly involved in the glutamate conversion into pyruvate were measured in guinea-pig renal cortex. 7. Renal arteriovenous-difference measurements revealed that in vivo the guinea-pig kidney adds glutamine and alanine to the circulating blood.

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