Can total prorenin in human plasma be determined by current activation methods?

Area of Science:

• Biochemistry
• Endocrinology
• Physiology

Background:

• Accurate determination of plasma prorenin is essential for evaluating its physiological significance.
• Current activation methods may not fully measure total prorenin or a known proportion of it.

Purpose of the Study:

• To investigate the effectiveness of different methods for determining total plasma prorenin.
• To explore potential synergism between cold and trypsin activation methods.

Main Methods:

• Extended cold activation of human plasma at -4°C.
• Trypsin titration of individual plasmas.
• Sequential application of cold and trypsin activation methods.

Main Results:

• Cold activation showed progressive prorenin increments over time, with individual variations.
• Trypsin activation did not consistently yield higher totals than cold activation.
• Sequential activation (trypsin before cold) demonstrated significant synergism, increasing prorenin estimates over 10-fold.
• Combined methods generally yielded higher prorenin totals than single methods.

Conclusions:

• Single activation methods may underestimate total plasma prorenin.
• Sequential activation, particularly trypsin followed by cold, is more effective in determining total prorenin.
• The sequence of activation is critical, with trypsin-after-cold activation being less effective due to potential plasma sensitization.