Renal nerve stimulation restores tubuloglomerular feedback after acute renal denervation. 1998

J Kurkus, and C Thorup, and A E Persson
Department of Nephrology, Lund University, Sweden.

Renal nerves play an important role in the setting of the sensitivity of the tubuloglomerular feedback (TGF) mechanism. We recently reported a time-dependent resetting of TGF to a lower sensitivity 3-4 h after acute unilateral renal denervation (aDNX). This effect persisted after 1 week, but was then less pronounced. To determine whether normal TGF sensitivity could be restored in aDNX kidneys by low-frequency renal nerve stimulation (RNS), the following experiments were performed. Rats with aDNX were prepared for micropuncture. In one experimental group proximal tubular free flow (Pt) and stop flow pressures (Psf) were measured during RNS at frequencies of 2, 4 and 6 Hz. In another series of experiments the TGF sensitivity was evaluated from the Psf responses at different loop perfusion rates after 20 min of RNS at a frequency of 2 Hz. The maximal drop in Psf (delta Psf) and the tubular flow rate at which half the maximal response in delta Psf was observed (turning point, TP), were recorded. At RNS frequencies of 2, 4 and 6 Hz, Pt decreased from the control level of 14.1 +/- 0.8-13.1 +/- 1.0, 12.4 +/- 1.1 and 11.2 +/- 0.8 mmHg (decrease 21%, P < 0.05), respectively, while at zero perfusion and during RNS at 2 and 4 Hz Psf decreased from 42.5 +/- 1.6 to 38.2 +/- 1.4 and 32.8 +/- 4.3 mmHg (decrease 23%, P < 0.05), respectively. The TGF characteristics were found to be reset from the normal sensitivity with TP of 19.0 +/- 1.1 nL min-1 and delta Psf of 8.7 +/- 0.9 mmHg to TP of 28.3 +/- 2.4 nL min-1 (increase 49%, P < 0.05) and delta Psf of 5.8 +/- 1.2 mmHg (decrease 33%) after aDNX. After 20 min of RNS at 2 Hz TP was normalized and delta Psf was 33% higher. Thus the present findings indicate that the resetting of the TGF sensitivity that occurred 2-3 h after aDNX could be partially restored by 20 min of RNS at a frequency of 2 Hz. These results imply that renal nerves have an important impact on the setting of the sensitivity of the TGF mechanism.

UI MeSH Term Description Entries
D007668 Kidney Body organ that filters blood for the secretion of URINE and that regulates ion concentrations. Kidneys
D007678 Kidney Glomerulus A cluster of convoluted capillaries beginning at each nephric tubule in the kidney and held together by connective tissue. Glomerulus, Kidney
D007687 Kidney Tubules, Proximal The renal tubule portion that extends from the BOWMAN CAPSULE in the KIDNEY CORTEX into the KIDNEY MEDULLA. The proximal tubule consists of a convoluted proximal segment in the cortex, and a distal straight segment descending into the medulla where it forms the U-shaped LOOP OF HENLE. Proximal Kidney Tubule,Proximal Renal Tubule,Kidney Tubule, Proximal,Proximal Kidney Tubules,Proximal Renal Tubules,Renal Tubule, Proximal,Renal Tubules, Proximal,Tubule, Proximal Kidney,Tubule, Proximal Renal,Tubules, Proximal Kidney,Tubules, Proximal Renal
D008297 Male Males
D012079 Renal Circulation The circulation of the BLOOD through the vessels of the KIDNEY. Kidney Circulation,Renal Blood Flow,Circulation, Kidney,Circulation, Renal,Blood Flow, Renal,Flow, Renal Blood
D003714 Denervation The resection or removal of the nerve to an organ or part. Laser Neurectomy,Neurectomy,Peripheral Neurectomy,Radiofrequency Neurotomy,Denervations,Laser Neurectomies,Neurectomies,Neurectomies, Laser,Neurectomies, Peripheral,Neurectomy, Laser,Neurectomy, Peripheral,Neurotomies, Radiofrequency,Neurotomy, Radiofrequency,Peripheral Neurectomies,Radiofrequency Neurotomies
D004558 Electric Stimulation Use of electric potential or currents to elicit biological responses. Stimulation, Electric,Electrical Stimulation,Electric Stimulations,Electrical Stimulations,Stimulation, Electrical,Stimulations, Electric,Stimulations, Electrical
D004573 Electrolytes Substances that dissociate into two or more ions, to some extent, in water. Solutions of electrolytes thus conduct an electric current and can be decomposed by it (ELECTROLYSIS). (Grant & Hackh's Chemical Dictionary, 5th ed) Electrolyte
D005246 Feedback A mechanism of communication within a system in that the input signal generates an output response which returns to influence the continued activity or productivity of that system. Feedbacks
D005919 Glomerular Filtration Rate The volume of water filtered out of plasma through glomerular capillary walls into Bowman's capsules per unit of time. It is considered to be equivalent to INULIN clearance. Filtration Rate, Glomerular,Filtration Rates, Glomerular,Glomerular Filtration Rates,Rate, Glomerular Filtration,Rates, Glomerular Filtration

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