Enzyme activities of the single juxtaglomerular apparatus in the rat kidney

Location of [125I]‐angiotensin II receptors on rat kidney cortex epithelial cells

“…Of the peripheral actions perhaps the least well understood is the mechanism by which AII stimulates salt and water re-absorption across transporting epithelia, particularly in the renal cortex. The synthesis and storage of renin within juxtaglomular cells (Granger et al, 1972) and the high concentration of converting enzyme present on the brushborders of the proximal tubule epithelia (Ward etal., 1975) strongly suggest an intrarenal site for AII production. It is likely therefore, that a degree of AII's antinatriuretic and antidiuretic effects are dueto a direct action of intrarenally produced hormone.…”

Converting enzyme inhibition and the kidney.

“…First, while the total amount of converting enzyme in the kidney is small, it is sharply localized to the juxtaglomerular apparatus where its action on the afferent and efferent arteriole would be maximal. 23 ' ** Second, the concentration of angiotensin II of lymph draining the kidney is substantially higher than in the arterial or renal venous plasma, again suggesting local generation." Third, converting enzyme inhibition with the nonapeptide, SQ 20,881, blocked the action of angiotensin I on the canine renal blood supply, suggesting that angiotensin I had to undergo hydrolysis to angiotensin II for activity, and that conversion happened within the kidney.…”

Superficial and Deep Juxtaglomerular Apparatus Renin Activity of the Rat Kidney EFFECT OF SURGICAL PREPARATION AND NaCl INTAKE

“…The generation of angiotensin and the determination of renin activity was performed with a modification of the methods of Dahlheim et al (8) and Granger et al (1). A single JGA was placed in a siliconized polyethylene tube containing 0.2 ml of cold (0-40C) sheep substrate, sonicated at 25 W for two 3-s intervals using a 3.0-mm probe tip.…”

“…A recent study by de Rouffignac, Bonvalet, and Menard (6), published while the current study was in progress, demonstrated a significant superficial to deep renin gradient in the rat, as did a previous indirect histochemical study (7). The major methodologic difference between direct studies of glomerular renin activity which demonstrated a renin activity gradient (3,6) and studies of juxtaglomerular renin activity which failed to demonstrate a gradient (1,8) was that in the latter the carotid artery or jugular vein was manipulated while in the former they were not. Brown, Davies, Lever, Parker, and Robertson directly visualized glomeruli in the rabbit cortex (3) and de Rouffignac et al (6) calculated individual renin content per glomerulus by quantifying the renin content of cortical fragments and estimating the number of glomeruli per fragment; Dahlheim, Granger, and Thurau (8) injected Evans blue dye into the jugular vein, and Granger et al (1) injected silicone-rubber into the carotid artery.…”