OFFICIAL USE OP” ¥ Dr. Dahl's group then evaluated the role of the kidneys in the induction of hypertension by a high salt diet. Their data show that if the kidney from a sensitive rat is transplanted into a resistant rat, the salt will quickly cause a rise in blood pressure. On the other hand, if the kidney frem a resistant rat is put into a sensitive rat, there is no change in blood pressure on salt loading. If a resistant kidney is transplanted into a hypertensive sensitive rat, the recipient responds by a drop in blood pressure. The group is now beginning to study the genetics of cholesterol metabolism, Their preliminary evidence indicates lack of an association between sensitivity to hypertension and cholesterol level. Following Dr. Dahl's presentation, there was again an extended and lively discussion. The next presentation was by Dr. Harold Atkins who gave an overview of the nuclear medicine program in the Brookhgyen Nefional, 7aporatory Radionuclides of particular interest, anc lude 123°? Xe, Tc and the short-lived isotopes including C, F, and . As one might surmise, there is an active program in improving the instramentation for scanning for these various isotopes. They have found that technicium-labeled red cells can be used in patients to do spleen scans. There is a need, however, to damage the labeled red cells so that they become trapped in the spleen. There is relatively little of the nuclide localized in the liver which is a considerable advantage over the conventional colloidal methods. Undamaged labeled cells remain in the circulation and consequently it is possible to visualize the heart and major blood vessels very well. Dr. Atkins showed a particularly impressive picture of a defect in the carotid artery. To visualize the kidney, they have used technicium-labeled DTPA. This material is cleared through the glomerulus but is not reabsorbed. Use of the labeled DTPA can also measure clearance rates from the plasma into the urine. Aortograms can be made and measurements of the extracellular space can also be made. The Se is used,principally to label amino acids to attempt to visualize the pancreas. F tryptophane looks particularly promising. They have noticed, however, that there are marked differences in the ratio of the amounts localized in the pancreas and kidney as a function of species. 1237 is used fer thyroid imaging and the very short half life and other physical characterighics of the nuclide make it very useful. In the past the use of labeled I was limited because it was uniformly contaminated with I-124. They are now able to get the I-123 almost completely pure. In addition to its use in thyroid scanning, there is a potential use in labeling albumins. OFFICIAL USE ONLY