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Characterization of two different affinity B2-kinin binding sites in rat glomeruli
C Emond1, C Pécher, J L Bascands
1INSERM U133, Institut Louis Bugnard, Faculté de Médecine Rangueil, Toulouse, France.
Agents and Actions. Supplements
|January 1, 1992
Summary
Researchers identified two distinct bradykinin B2 receptors in rat glomeruli, differing in affinity and density. This finding clarifies the role of bradykinin in kidney function and glomerular filtration rate control.
Area of Science:
- Nephrology
- Pharmacology
- Molecular Biology
Background:
- A bradykinin (BK) receptor in rat renal mesangial cells is linked to PGE2 release and IP3 formation, suggesting a role in cell contraction and glomerular filtration rate (GFR).
- The existence of a unique glomerular BK receptor has not been definitively established.
Purpose of the Study:
- To determine if the mesangial BK receptor is the sole BK receptor in the glomerulus.
- To characterize BK binding sites in isolated rat glomeruli.
Main Methods:
- Binding studies were conducted on decapsulated isolated rat glomeruli.
- Scatchard analysis was used to analyze binding data.
- Optimal solubilization conditions were determined using various detergents (Triton X-100, CHAPS, n-octyl beta-D glucopyranoside) and incubation parameters.
Main Results:
- Scatchard analysis revealed two distinct B2-kinin binding sites in isolated glomeruli with differing affinities and densities.
- Optimal binding was achieved using 25 mM n-octyl beta-D glucopyranoside for 60 minutes at 4°C with shaking.
- Similar binding characteristics were observed in both 12,000 x g and 100,000 x g supernatants, indicating the presence of two B2-kinin receptors with different affinities.
Conclusions:
- Rat glomeruli possess at least two B2-kinin receptors with distinct binding characteristics.
- These findings contribute to understanding the role of bradykinin in renal physiology.