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 +/- 0.85 contractions/min, a mean [Na+] of 91.0 +/- 33.3 mEq/kg net weight, a mean [K+] of 18.9 +/- 6.0 mEq/kg net weight. The frequency of spontaneous activity from the middle pelvis and distal pelvis decreases to mean values of 2.76 +/- 0.60 and 1.82 +/- 0.56 contractions/min. The corresponding values for [Na+] and [K+] are 78.0 +/- 27.7 and 11.8 +/- 4.7 for the middle pelvis and 66.6 +/- 32.7 and 9.75 +/- 3.4 for the distal pelvis, respectively. Normalized regression curves indicate a [Na+]gradient variation of delta [Na+] = 67.1 +/- 0.07 delta F and a [K+] gradient of delta [K+] = 39.8 - 0.06 delta F + 0.01 delta F2. Spatially, the variation of [Na+] and [K+] with distance. D, within the pelvis is given by [Na+] = 119 - 14D + D2 and [K+] = 26 - 11D + 2D2. It is concluded from this study that there is a frequency gradient between proximal renal pelvis and ureteropelvic junction which is significantly interdependent upon the cellular [Na+] on [K+] concentration gradient.