Use of Isotopes in Ion Transport Studies

　In discussing the broad topic of "The Use of Isotopes in Ion Transport Studies," it has seemed best to confine myself to an account of one particular scientific investigation which has relied heavily and continuously on the use of isotopes. This investigation, which is concerned with the basic mechanism governing the absorption of water by the proximal tubule of the kidney, was initiated in our loboratory in 1953 and has occupied our attention continuously since that time.