Sphincteric action of the pelvicalyceal junction and pacemaker activity in human kidney

The effect of elevation of renal pelvic pressure on pacemaker activity was examined in 5 isolated human kidneys. Pressure fluctuations transmitted from renal pelvic contractions first appeared in pressure tracings from the upper renal calyx as renal pelvic pressure exceeded 25 cm H2O. This finding suggests that the pelvicalyceal junction acts as a sphincter which can withstand pelvic pressures of about 25 cm H2O. The upper renal calyx contracted rhythmically at a rate of 10 times per minute when the pelvic pressure was low. At high pelvic pressures, upper calyceal contraction frequency decreased although its rhythm remained regular. As renal pelvic pressure increased, the frequency of renal pelvic contractions increased to a level that corresponded in a 1:1 ratio with contractions of the upper calyx.