C-peptide normalizes glomerular filtration rate in hyperfiltrating conscious diabetic rats

Area of Science:

• Nephrology
• Endocrinology
• Physiology

Background:

• Kidney oxygen consumption is significantly linked to tubular electrolyte transport.
• Diabetes mellitus is associated with increased kidney oxygen usage, primarily due to enhanced tubular electrolyte transport driven by glomerular hyperfiltration.
• Previous research indicates C-peptide can normalize glomerular filtration rate (GFR) in diabetic models.

Purpose of the Study:

• To validate a novel, non-invasive method for precise and repeatable GFR measurements in conscious rats.
• To evaluate the effect of C-peptide on GFR in a streptozotocin-induced diabetic rat model using the validated method.

Main Methods:

• GFR was measured in conscious rats using plasma clearance of FITC-inulin after a single bolus injection.
• Non-compartmental pharmacokinetic analysis was employed to calculate FITC-inulin clearance.
• GFR was assessed in normoglycemic controls and diabetic rats, both before and after C-peptide administration.

Main Results:

• The novel GFR measurement method yielded results comparable to traditional methods on anesthetized rats.
• C-peptide did not affect GFR in normoglycemic control rats.
• Diabetic rats exhibited elevated GFR, which was significantly normalized following C-peptide administration.

Conclusions:

• The validated method allows for accurate, repetitive GFR measurements in conscious rats.
• C-peptide effectively normalizes the hyperfiltration observed in conscious diabetic rats, mirroring findings in anesthetized models.
• This study supports C-peptide as a potential therapeutic agent for managing hyperfiltration in diabetic nephropathy.