Extraction, purification, and assay of human renin free of angiotensinase

Renin activation in the venous plasma from the involved kidney in the patient with renal hypertension

Measurements of plasma renin activity (PRA) in renal vein blood from the ischemic kidney are reported to be generally higher than from the contralateral kidney. Importance of factors other than renin content of renal venous plasma has not been investigated. Initial rate measurements of angiotensin generation with added excess of homologous renin (Plasma Renin Substrate Activity [PRSA]-20 min) were made in bilateral renal venous plasma from 31 patients suspected of suffering from unilateral renal hypertension. The mean values from the involved vs. the contralateral kidney were 551 vs. 331 ng respectively of angiotensin II equivalents generated per milliliter of plasma per 20 min of incubation. The measurement of maximal angiotensin generation under the same conditions with incubation prolonged to 3 hr (PRSA-180 min), however, were bilaterally equal in renal venous plasma from selected patients with renal hypertension who showed distinct differences in PRSA-20 min and PRA measurements. Prior extraction of plasma lipids did not significantly change the bilateral renal venous PRSA-20 min determinations. Stimulation of endogenous renin release in normal dogs did not change the PRSA determinations. The data suggest strongly the presence of a "renin activating" mechanism in the renal venous plasma from the involved kidney of patients with renal hypertension.

Central components of the renin-angiotensin system

1. Re-establishment of renal blood flow after total renal ischaemia of 4 h duration causes a pressor response in pentobarbitone anaesthetized rats and cats.2. The pressor response is related to the release of renin from the ischaemic kidney.3. Spinal section at any cervical level or stellate ganglionectomy abolishes the pressor response but spinal section caudad to the thorax or vagotomy and treatment with hexamethonium have no effect.4. Spinal section and stellate ganglionectomy interfere with the release of renin and with the pressor response to angiotensin.

Angiotensin and renin in rat and dog brain

An enzyme with the characteristics of classical renin was isolated from brain extracts of nephrectomized dogs. This enzyme is thermolabile, nondialyzable, and forms a vasoconstrictive material when incubated with renin plasma substrate at pH 7. A short lasting pressor activity was also found in brain extracts of dogs and rats. This activity was due to a substance identified by chemical and pharmacological tests as angiotensin. Countercurrent distribution of brain extracts of rats showed that 38% of the pressor activity corresponded to angiotensin II and the remainder to angiotensin I. A remarkable correlation was found between angiotensin and norepinphrine concentrations in different portions of the encephalon of the dog.