Total [Na+] and [K+] gradient in the pyeloureter.

The gradient of cellular [Na+] on [K+] ion within the renal pelvis of the rabbit was correlated with the autorhythmicity of the proximal, middle, distal and ureteropelvic regions of this structure. The results show that the maximum frequency of spontaneous pacemaker contractions occur at the proximal pelvis with a mean frequency of 4.97 +/- 0.