Tanenao Eto

Is single oral administration of captopril beneficial in screening for primary aldosteronism

Plasma renin activity (PRA) and plasma aldosterone concentration (PAC) were measured in 19 cases with primary aldosteronism (PA) and in 72 with essential hypertension (EHT) to differentiate the two disorders during the following conditions on normal salt diet: after overnight recumbency (basal state) and 2 hours after oral administration of 25 mg of captopril. Screening criteria were determined so that all PA patients were diagnosed as positive, and their specificities were compared with those of other conventional screening methods for PA. After captopril administration, the specificity of a criterion based on a combination of PAC and PAC/PRA ratio was 93% and positive predictive value was 79%. This criterion was superior to blood pressure response to angiotension II analog infusion, PRA on salt depletion, and to PAC on salt loading. However, higher specificity (97%) and positive predictive value (90%) were obtained from a criterion based on a combination of basal PAC and PAC/PRA ratio. Therefore, the use of a combination criterion based on PAC and PAC/PRA ratio at basal state rather than after captopril administration may give a satisfactory result in the screening for PA.

Increased capillary permeability in muscularis layer of rat intestine caused by kidney extract.

SummaryKidney extract and synthetic angiotensin II were injected into bilaterally nephrectomized rats in dosages capable of raising the mean arterial pressure by about 20 mmHg. Changes in ultrastructure and permeability for ferritin molecules were then examined in capillaries located in muscularis layer of the intestinal walls. Kidney extract with a high renin content was obtained from the renal cortex of rats by means of stepwise centrifugation methods. Animals injected with saline served as controls. In rats receiving kidney extract tissue edema was observed in the spaces around the blood and lymphatic capillaries. In these spaces ferritin molecules accumulated in high concentration indicating plasma protein leakage. Ferritin molecules within the endothelium were restricted within plasmalemmal vesicles, but were not found within interendothelial junctions or within the cytoplasmic matrix. Morphometric analysis of vesicular transport in the endothelial cells revealed a significant increase in labeling rate for the vesicles with ferritin molecules. These results suggest that the kidney extract contains substance(s) which increase capillary permeability for plasma proteins at least via increased vesicular transport, resulting in tissue edema.