Changes in active and inactive renin with haemodialysis

Area of Science:

• Nephrology
• Endocrinology
• Renal Physiology

Background:

• Plasma renin concentration (PRC) plays a crucial role in blood pressure regulation.
• Understanding the behavior of active (APRC) and inactive (IPRC) renin during hemodialysis is important for managing hypertensive patients with kidney disease.
• Previous research has not fully elucidated the dynamics of APRC and IPRC in the context of hemodialysis and associated physiological changes.

Purpose of the Study:

• To investigate the relationship between active and inactive plasma renin concentrations (PRC) during hemodialysis.
• To assess the influence of blood pressure and body weight changes on APRC and IPRC during hemodialysis.
• To determine if hemodialysis affects renin activation or clearance.

Main Methods:

• Plasma samples were collected from patients undergoing hemodialysis with varying degrees of renal function (remnant kidneys or anephric).
• Inactive renin was activated by acidification.
• Renin assays were performed using an enzyme kinetic technique with sheep substrate and angiotensin I radioimmunoassay, with cryoactivation excluded.

Main Results:

• A significant inverse relationship was observed between the proportion of inactive PRC and active PRC in pre-dialysis plasma across the entire patient group (p < 0.001).
• APRC and IPRC levels did not change significantly with heparinization, nor was renin activation observed across the dialyzer.
• Hemodialysis-induced body weight reduction (up to 3 kg) did not consistently alter APRC or IPRC, and blood pressure showed no significant correlation with either renin form during dialysis.

Conclusions:

• The findings suggest a preferential secretion of active renin or consumption of inactive renin zymogen, as indicated by the high APRC and low IPRC:APRC ratio.
• Hemodialysis itself, blood pressure fluctuations, and body weight changes do not appear to significantly impact the balance of active and inactive plasma renin concentrations.
• The study highlights the complex regulation of renin forms in patients with chronic kidney disease undergoing hemodialysis.