Movement of electrolytes across the wall of the urinary bladder in dogs

The transfer of certain electrolytes (Na+, K+, Cl–, H+) through the wall of the isolated urinary bladder has been studied in the dog. When test solutions are introduced into the bladder, changes in the concentration of these ions occur in the direction of their concentration gradient with plasma. The magnitude of these changes depends chiefly upon the magnitude of the concentration gradient but is influenced, as well, by the time the solution is allowed to remain in the bladder, by the pH of the solution and probably by its volume. By the use of Na22 it has been shown that sodium moves through the bladder wall in both directions at the same time. The movement of electrolytes into and out of the bladder appears to be passive. It is reaffirmed that the urinary bladder is not an impermeable reservoir and that, in some circumstances, the composition of bladder urine need not be identical with that of the urine as it leaves the kidney.