Active and inactive renins in human urine

Area of Science:

• Nephrology
• Endocrinology
• Biochemistry

Background:

• Renin, an enzyme crucial for blood pressure regulation, exists in active and inactive forms.
• Understanding renin excretion patterns in renal disease is vital for patient management.
• Previous research has primarily focused on plasma renin levels, with less attention to urinary excretion.

Purpose of the Study:

• To investigate the urinary excretion of active and inactive renin in healthy individuals and patients with hypertensive or renal disease.
• To explore correlations between urinary renin forms, plasma renin levels, and proteinuria.
• To characterize the properties of urinary active and inactive renin.

Main Methods:

• Collected and analyzed urinary samples from normal subjects and patients with hypertensive or renal disease.
• Measured active and inactive renin excretion and correlated findings with plasma renin levels and proteinuria.
• Utilized gel filtration chromatography to determine the molecular weights of urinary renins.
• Investigated the effects of acidification, trypsin, and cold exposure on urinary renin activity.

Main Results:

• Observed excessive urinary excretion of both active and inactive renin in some patients, independent of plasma levels or proteinuria.
• Found a correlation between inactive and active renin excretion, with lower clearance for inactive renin.
• Urinary renin activity increased with acidification and trypsin treatment.
• Gel filtration revealed multiple peaks for both active and inactive urinary renins between 45,000 and 64,000 molecular weight.

Conclusions:

• Urinary active and inactive renin excretion can be excessive in hypertensive and renal disease patients.
• Inactive renin has a lower urinary clearance than active renin.
• Urinary renin exists in multiple molecular forms and its activity is influenced by pH and enzymatic treatment.