Different secretion patterns of active and inactive renin in man

Area of Science:

• Endocrinology
• Renal Physiology
• Hypertension Research

Background:

• Renin exists in active and inactive forms, with inactive renin being more abundant in plasma.
• The physiological role and regulation of inactive renin are not fully understood.
• Understanding renin kinetics is crucial for managing hypertension.

Purpose of the Study:

• To compare concentrations of active and inactive renin in normal and hypertensive subjects.
• To investigate the differential responses of active and inactive renin to various physiological and pharmacological stimuli.
• To elucidate the distinct release mechanisms of active and inactive renin.

Main Methods:

• Measurement of active and inactive renin concentrations in plasma samples from healthy individuals and hypertensive patients.
• Assessment of renin levels following hyperacute (saralasin infusion) and acute (frusemide/ambulation) stimulation.
• Evaluation of renin responses to short-term (5 days) and long-term (3 months) thiazide treatment.
• Analysis of renin distribution in renovascular hypertension patients before and after saralasin infusion.

Main Results:

• Inactive renin was 4-5 times higher than active renin in normal and untreated hypertensive subjects.
• Plasma angiotensin II correlated with active renin, not inactive renin.
• Saralasin infusion increased active renin but not inactive renin.
• Frusemide/ambulation and short-term thiazide increased active renin more than inactive renin.
• Long-term thiazide treatment significantly increased both active and inactive renin, with a greater fold increase in inactive renin.

Conclusions:

• Inactive renin is significantly more abundant than active renin in human plasma.
• Active and inactive renin exhibit differential responses to various stimuli, indicating distinct regulatory pathways.
• The differing responses suggest that active and inactive renin have different secretion or release time constants in humans.