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Single-channel Analysis and Calcium Imaging in the Podocytes of the Freshly Isolated Glomeruli
Published on: June 27, 2015
Arachidonate metabolites and the control of glomerular function
Federation Proceedings
|November 1, 1983
Summary
Glomerular mesangial cells regulate filtration rate via contraction, influenced by constrictors like angiotensin II and dilators like prostaglandins. Thromboxane A2 plays a key role in nephrotoxic serum nephritis, impacting glomerular filtration rate.
Area of Science:
- Nephrology
- Renal Physiology
- Molecular Biology
Background:
- The glomerulus regulates glomerular filtration rate (GFR) through mesangial cell contraction.
- Angiotensin II (AII) and arginine vasopressin (AVP) stimulate mesangial contraction and vasodilatory prostaglandin (PG) production.
- Interactions between these constrictors and dilators within the glomerulus are complex.
Purpose of the Study:
- To investigate the interplay between constrictive and dilatory factors in glomerular function.
- To elucidate the role of prostaglandins and thromboxane A2 in glomerular contraction and GFR regulation.
- To examine the impact of nephrotoxic serum nephritis (NSN) on glomerular hemodynamics and the role of thromboxane A2.
Main Methods:
- Measurement of prostaglandin synthesis (PGF2 alpha, PGE2, 6-keto-PGF1 alpha, TxB2) in normal rat glomeruli and isolated cells.
- Assessment of glomerular contraction in response to AII, arachidonate, PGE2, and PG inhibitors.
- Evaluation of glomerular thromboxane A2 production and its correlation with GFR and filtration fraction in acute NSN.
- Testing the effect of TxA2 synthesis inhibition on GFR and filtration fraction in NSN.
Main Results:
- Normal glomeruli produce PGF2 alpha > PGE2 > 6-keto-PGF1 alpha = TxB2.
- AVP and AII stimulation of glomerular cells preferentially increased PGE2 synthesis, suggesting an intraglomerular feedback loop.
- Arachidonate or PGE2 preincubation reduced AII-induced glomerular contraction, while PG inhibition enhanced it.
- In acute NSN, increased glomerular TxA2 production correlated with decreased GFR and filtration fraction.
- Inhibition of TxA2 synthesis in NSN normalized GFR and filtration fraction within 1-3 hours.
Conclusions:
- Vasodilatory prostaglandins play a significant physiological role in modulating AII-induced glomerular contraction.
- Arachidonate metabolite thromboxane A2 exerts a direct mesangial contractile effect.
- Thromboxane A2 is implicated in the GFR reduction observed during the acute phase of NSN.
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