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Cytochrome P450-derived renal HETEs: storage and release
M A Carroll1, M Balazy, D D Huang
1Department of Pharmacology, New York Medical College, Valhalla, USA.
Kidney International
|June 1, 1997
Summary
This study developed a gas chromatography-mass spectrometry assay to measure cytochrome P450 (P450)-hydroxyeicosatetraenoic acids (HETEs) in rabbit kidneys. Angiotensin II stimulates the release of these P450-HETEs, which are stored in kidney lipids.
Area of Science:
- Biochemistry
- Renal Physiology
- Pharmacology
Background:
- Cytochrome P450 (P450) enzymes produce hydroxyeicosatetraenoic acids (HETEs).
- HETEs play roles in renal function, including vasodilation and ion transport.
- Endogenous HETE production and storage in the kidney are not fully understood.
Purpose of the Study:
- To establish a method for profiling and quantifying endogenous P450-HETEs in the rabbit kidney.
- To investigate the release of P450-HETEs in response to hormonal stimulation (angiotensin II).
- To identify the lipid fractions where P450-HETEs are stored within the kidney.
Main Methods:
- Gas chromatography-mass spectrometry (GC-MS) assay development.
- Isolated perfused rabbit kidney model.
- Hormonal stimulation with angiotensin II.
- Lipid extraction, separation (HPLC), and hydrolysis for HETE quantification.
Main Results:
- Angiotensin II significantly increased the release of P450-HETEs (16-, 17-, 18-, 19-, and 20-HETE) into urinary and venous effluents.
- P450 inhibition reduced basal HETE release but did not abolish Ang II-induced release.
- P450-HETEs were found esterified in neutral lipids and phospholipids in both cortical and medullary tissues, with higher concentrations in the cortex.
Conclusions:
- A novel assay allows for the measurement of endogenous P450-HETEs in the kidney.
- Angiotensin II stimulates the release of vasodilatory and ATPase-inhibiting P450-HETEs.
- P450-HETEs are stored in kidney lipids, suggesting a mechanism for their regulated release.