140 



RADIOISOTOPES IN BIOLOGY AND AGRICULTURE 



(a) 



some route. Unless quantitative delivery is assured, the experimental 

 results will have little or no meaning. Often, if the dose is only partially 

 delivered, the animal will be unsuitable for further work. Thus it is very 

 important that the radioactivity be quantitatively administered in a high 

 proportion of the animals, especially if the individuals have been on treat- 

 ment and there are only limited numbers available. It is emphasized 

 that only extensive practice, which can be done with inert solutions and 



cull animals, will result in satisfactory 

 proficiency. Descriptions of conven- 

 tional methods of administration, 

 especially to laboratory animals, may 

 be found in references (11, 13, 18). 



Two methods for the quantitative 

 delivery of a radioactive solution are 

 illustrated in Fig. 4-18 (17). The ap- 

 paratus in (a) is assembled from a 

 metal three-way stopcock and two 

 syringes. In operation, the solution 

 to be administered is measured into 

 the open syringe B, is drawn into the 

 horizontal syringe A, and, with ma- 

 nipulation of the stopcock C, it is 

 delivered to the site of injection. 

 Wash solution is placed in the open 

 syringe, and the procedure is repeated. 

 The advantages of this method are 

 that small amounts of the active solu- 

 tion, delivered to the syringe by a 

 micropipette, can be injected quanti- 

 tatively, since it is not necessary to 

 measure the volume by the syringe 

 markings. Also the rinsing of the 

 system is conveniently accomplished without removing the needle from 

 the site of injection, and the system can be well shielded if required, since 

 it is never necessary to read the syringe markings. A useful modification 

 is to use syringe A for the dosing solution and to replace syringe B with 

 rubber tubing that dips into wash solution. 



Another method that has been found convenient is illustrated in Fig. 

 4-186. In this procedure, syringe A, which is used for the wash solution, 

 is connected to the injection needle or stomach tube by a convenient length 

 of soft rubber tubing E. In operation, the radioactive solution is injected 

 into the lumen of the connecting tube, both the dosing and wash syringes 

 being operated simultaneously. The dosing syringe B can be calibrated 



Fig. 4-18. Two methods for the quan- 

 titative delivery of radioactive solu- 

 tions. [From Sam. L. Hansard, C. L 

 Coinar, and M. P. Plumlee, Radio- 

 isotope Procedures with Farm Animals 

 Nucleonics, 9: 13-25, 38-45 (1951).] 



