Functional integrity of proximal tubule cells: Effects of temperature and preservation solutions

Electrophysiologic and morphologic changes during cooling and perfusion with preservation solutions in isolated perfused proximal straight tubules from Swiss white mice were investigated. In standard Ringer-substrate solution, cooling from 37°C to 22 and 4°C depolarized both transepithelial potential and basolateral cell membrane potential. Basolateral K⁺ transference number and cell membrane conductances were also significantly reduced. An increase in intracellular Na⁺ activity was observed only during cooling from 37 to 4°C. No cell swelling was detected when tubules were perfused with Ringer-substrate solution at all three temperatures up to 1 h. Perfusion with Euro-Collins' (EC) solution at 37°C resulted in rapid cell swelling, associated with rapid deterioration of transepithelial potential. Substitution of glucose with mannitol abolished the damaging effect of EC solution at 37°C. EC perfusion at 22°C also led to cell swelling and deterioration of transepithelial potential, but after a 10-min delay. In comparison, perfusion with University of Wisconsin (UW) solution at 22 or 37°C had no effect on cell volume. Less damage to transepithelial potential was observed after the UW perfusion. It was concluded that EC solution is more damaging than UW solution to kidney tubules at 22 and 37°C. The presence of EC solution in the renal interstitium during the rewarming phase may contribute significantly to reperfusion injuries in kidney transplantation.