Pyelonephritis. III. Observations on the Association between Chronic Pyelonephritis and Hypertension in the Rat.

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Abstract
An experiment was designed to investigate the possible etiologic relationship between kidney infection and hypertension in rats in whom chronic progressive pyelonephritis was produced without ureteral ob -struction. Four groups were studied A chronic enterococcal pyelonephritis received one injection of Str. faecalis intravenously; B chronic enterococcal pyelonephritis with acute exacerbations of enterococcal infection of Str. faecalis intravenously and after an interval of six months four repeated injections of the same Str. faecalis at two month intervals; C chronic enterococcal pyelonephritis with acute exacerbations of E. coli infection - treated similarly to B except that repeated infections were produced by injection of a strain of E. coli; D controls uninfected animals. During 20 months of observation, blood pressures were recorded monthly. The rats were sacrificed and weighed and organs studied. No difference in blood pressure was noted between any of the groups. Histologic examination revealed microscopic scars on the cortical surfaces of a majority of kidneys examined in Groups A, B and C which consisted of areas of loss of renal parenchyma, presence of fibrous tissue, infiltrating mono-nuclear cells, dilated tubules filled with "colloid" casts and minimal to moderate periglomerular fibrosis. Limited alterations, mostly sclerotic changes associated with aging processes were noted in the arteries and arterioles. These observations suggest that chronic, progressive, nonobstructive, enterococcal pyelonephritis in the rat is not associated with hypertension. It is suggested that this may be related to the absence of significant arteriolar nephrosclerosis.