Studies on trypsin activation of inactive renin in rat plasma

N. Glorioso, P. Madeddu, P. Dessi-Fulgheri, V. Anania, F. Meloni, G. Fois, F. Bandiera, A. Rappelli

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The experimental conditions of trypsin activation of inactive renin in rat plasma have been studied. Our results showed that the pH optimum of trypsin-activated renin is 6.2, the same as that of rat plasma active renin. Trypsin concentration and incubation time might also interfere with the activation process. Trypsin concentration below 2 mg/ml cannot activate inactive renin. Trypsin at a concentration of 6 mg/ml for 1 min. can cleave dialyzable fragments from renin substrate which can generate Angiotensin I at 37°C with a pH optimum of 5.3 but which do not affect Angiotensin generation at pH 6.2. Longer incubations (more than 2 min.), on the contrary, can produce a cleavage at 4°C of Angiotensin I containing fragments directly from renin substrate strongly interfering with measurements of renin activity at pH 6.2. Trypsin concentrations lower than endogenous rat plasma anti-trypsin activity do not activate inactive renin. Much higher concentrations of trypsin, however, are needed to obtain optimum activation of inactive renin. in average, 40% of the total circulating renin in rat plasma can be activated by trypsin.

Original languageEnglish
Pages (from-to)2203-2212
Number of pages10
JournalClinical and Experimental Hypertension
Issue number11-12
Publication statusPublished - 1982

ASJC Scopus subject areas

  • Internal Medicine
  • Physiology


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