| Abstract: | The effect of warm ischemia on the transmembrane transport of potassium in dog kidney slices was studied by measurement of the uptake of 42K. The requirement for steady-state conditions concerning the intracellular potassium concentration was thereby studied. The total potassium content in the slices was found to be constant between 120 and 180 min incubation at both 25 and 37 degrees C. The cell water calculated from the total tissue water and 14C-inulin space in the dog kidney slices amounted to 38 ml-100 g wet weight-1 at 37 degrees C and 45 ml-100 g wet weight-1 at 25 degrees C and was found to remain constant for the incubation interval 120--180 min. The major part of the tissue uptake of 42K could be described by one single mono-exponential function under these conditions. The transmembrane influx at 37 degrees C calculated by using a modified Keynes formula amounted to 1.70 mmol K+-kg wet weight-1-min-1 after no warm ischemia and to 0.89 mmol K+-kg wet weight-1-min-1 after 2 h warm ischemia. The corresponding values for incubation at 25 degrees C were 1.26 and 0.77 mmol K+-kg wet weight-1-min-1, respectively. In the slices incubated at 25 degrees C, the potassium content was higher and the sodium content lower than in slices incubated at 37 degrees C. |
