Single Proximal Tubules of the Necturus Kidney. Methods for Micropuncture and Microperfusion

Abstract

Procedures for the collection of tubular fluid and for stopped flow perfusions of the single proximal tubule of the kidney of Necturus maculosus are described. The method used in collection experiments is essentially the same as that developed by Richards and Walker ( Am. J. Physiol. 118: 111, 1937). The method used for stopped flow perfusion is a modification of the method of these authors. A proximal tubule in vivo is blocked with oil at both ends and the intervening space is filled with a perfusion fluid. After a suitable period (for instance, 20 min.), the fluid is withdrawn. By this method perfusion fluids of any desired composition are allowed to remain within the tubular lumen for an arbitrary period of time prior to collection and analysis. Water movement in the tubule is measured using C14 inulin. 27 samples of ureteral urine collected from 10 animals had a Na concentration of 2.8 ± 1.7 mEq/l. Data on the electrolyte composition of Necturus blood are presented, consistent with values given by other authors.