Nephron Stop-Flow Pressure Response to Obstruction for 24 Hours in the Rat Kidney

tion significantly reduced stop-flow and estimated glo-merular capillary pressures in nephrons accessible to micropuncture in obstructed kidneys. In kidneys with-out ureteral obstruction, a similar repsonse occurred in single tubules blocked for 24 h without affecting nearby unblocked tubules. Thus, the response to tubular ob-struction occurs on an individual nephron basis and re-sults from constriction of individual afferent arterioles. The mechanism leading to the response is unknown, but a feedback mechanism operating through the juxtaglo-merular apparatus of individual nephrons is an attractive possibility