Examination of the relationship of renin release to hypertension produced in the rabbit by renal-artery constriction

Renin and acute circulatory renal failure in the rabbit

Plasma renin concentration (PRC) was measured in 25 rabbits before and 6, 24, or 72 hours after subcutaneous injection of glycerol. Renal failure and tubular necrosis developed in most animals and PRC rose sixfold to a maximum at 24 hours. Small insignificant changes of PRC were present at 6 and 72 hours. None of these changes was observed in a control group of nine animals killed 24 hours after an injection of saline. The amount of renin extractable from single superficial glomeruli and from renal cortical tissue was reduced after injection of glycerol. In a second study of 11 anesthetized rabbits, renal venous PRC increased on average from 151 to 1810 units/liter following a 4-hour period of renal artery occlusion. Arterial PRC did not change significantly during this time, but the kidneys showed histological changes of acute tubular necrosis. These experiments are compatible with the suggestion that renin is involved in the pathogenesis of acute circulatory renal failure.

The progressive pressor response to angiotensin in the rabbit

1. The threshold for any detectable rise of systemic arterial pressure during the prolonged intravenous administration of angiotensin to conscious rabbits was observed to be an infusion rate of 0.003-0.006 mug.kg(-1).min(-1).2. At infusion rates between threshold and 0.04 mug.kg(-1).min(-1) the systemic arterial pressure rose progressively over a 3- to 7-day period to a plateau.3. On stopping the angiotensin infusion the blood pressure fell rapidly back to its base line much faster than it rose during the infusion. The time taken to reach control values was approximately related to the duration of the infusion.4. At infusion rates of about 0.05 mug.kg(-1).min(-1) the full rise of blood pressure developed within a few minutes, and could be sustained without change for many days. At higher rates the blood pressure diminished with time.5. Diurnal fluctuations of blood pressure were often seen during prolonged infusions of angiotensin at low rates; and more rapid fluctuations of blood pressure over an hour or two were frequently encountered immediately after an infusion was turned off.6. The possible role of angiotensin in producing chronic renal hypertension is discussed in the light of these observations.