THE NORMAL INTERPHASE IN THE POLYURIA WHICH FOLLOWS SECTION OF THE SUPRAOPTICO-HYPOPHYSIAL TRACTS IN THE DOG

¹ The Departments of Pharmacology, University of Cambridge, and of Physiology, University of Leeds

1. Four facts have been established concerning the period from the 6th to 11th days following section of the supraoptico-hypophysial tracts in the dog: (a) The daily urine volume is low (the "normal interphase" of Fisher, Ingram and Ranson [1938] between the temporary and permanent polyurias). (b) There is no diuretic response to administered water. Neither (a) nor (b) occurs following operative removal of the posterior lobe of the pituitary. (c) Sodium chloride administered by stomach tube in isotonic solution is excreted freely but in a small volume of urine of high chloride concentration. (d) Antidiuretic activity is present in the urine.

2. These facts indicate, and are adequately explained by, the conclusion that during the 6th-llth days after section of the tracts active material escapes from the degenerating pars nervosa of the pituitary into the blood stream at rates up to 0·3 mU per min.

Note:

I wish to acknowledge the assistance of Professor E. B. Verney in some of the earlier operative work of this paper.