Nuclear Medicine Technology and Other Health Applications Interrelationship becween Genetic and Environmental Pactors Project Title: in Clinical and Experimental Hypertension 15, Relationship to Other Projects: (Cont'd.) RX-01-03-(b) Freis at the VA Hospital in Washington, D. C. is studying the influence of dietary NaCl on the blood pressure of the SHR from the standpoint of modifying BP by anti-hypertensive drugs. 16, Technical Progress in FY 1973: The effect of renal transplants on the chronic blood pressure. response was studied in the two strains of rats with opposite genetic propensities to ca SORE Se ee Woe hypertension, 113 rats survived an average of 4 months (range 1-14) after this procedure, Among animals maintained on a low NaCl diet, blood pressure was not significantly affected when the recipient animal and its renal homograft came from the same strain; however, animals from the hypertension- oe resistant strain with a renal homograft from the hypertension-prone strain had higher pressures whereas hypertension-prone rats with a homograft from the hypertension-resistant strain had Lower pressures than their respective controls, Thus, the phenotypic response--blood pressure--was more influenced by the genotype of the renal homograft than by the genotype of the recipient, ve 4 OS ot we ot The continuing work with renal homografts has demonstrated, for the first time, that at least one of the genetically determined influences on blood pressure resides in the kidney, This technically difficult study is being c™ actively pursued, The influence of renal autografts on BP is being studied to determine whether subtle sub-clinical rejection may be occurring. Among animals from the S strain with salt-induced hypertension, it appears that kidneys from the hypertension-resistant rats lower the BP of such hypertensive recipients . - whereas kidneys from the hypertension-prone strain either result in no change or a further elevation in hypertensive recipients, These data, then, are compatible with the initial experiment obtained in non-hypertensive recipients, i.e,, the kidneys from the R strain tend to lower BP to normal levels whereas kidneys from the § strain tend to raise BP above normal. , In continuation of the study on influence of renal parenchymal injury on BP as modified by genetic background, the influence of prolonged anesthesia (animals were anesthetized for approximately 3 hours) and, in right uni- nephrectomized rats, of artery for 1 hour, were operations. These data impreapéon is that: a) anoxic injury produced by clamping the left renal explored in animals not subjected to renal transplant are being analyzed statistically but the preliminary anesthesia is without effect but, b) anoxia for one heaxs combined with added dietary NaCl results in some hypertension even among @ts ordinarily resistant to it. This could have significant clinical implications among individuals with various degrees of impaired renal blood flow or among the increasing number of people who receive renal homografts which will have necessarily been anoxic for a variable period prior to and during surgery. It would also aid in explaining why salt-fed R rats with R renal homografts or autografts sometimes develop hypertension, (See Continuation Sheet) LE V920b RX-48