scholarly journals Feedback regulation of nephron filtration rate during pharmacologic interference with the renin-angiotensin and adrenergic systems in rats

1979 ◽  
Vol 15 (5) ◽  
pp. 473-486 ◽  
Author(s):  
Nicholas Stowe ◽  
Jürgen Schnermann ◽  
Monika Hermle
Keyword(s):  
Filtration Rate ◽  
Feedback Regulation ◽  
Renin Angiotensin ◽  
Nephron Filtration Rate ◽  
Adrenergic Systems

Feedback control of glomerular filtration rate in isolated, blood-perfused dog kidneys

1977 ◽  
Vol 233 (3) ◽  
pp. F217-F224 ◽  
Author(s):  
J. Schnermann ◽  
N. Stowe ◽  
S. Yarimizu ◽  
M. Magnsusson ◽  
G. Tingwald
Keyword(s):  
Filtration Rate ◽  
Feedback Regulation ◽  
Tubuloglomerular Feedback ◽  
Sodium Reabsorption ◽  
Loop Of Henle ◽  
Nephron Filtration Rate ◽  
Proximal Tubular ◽  
Flow Through ◽  
Induced Changes ◽  
Isolated Kidneys

Micropuncture studies were done in isolated, blood-perfused dog kidneys to investigate the intrarenal nature of tubuloglomerular feedback regulation of nephron filtration rate. Collections were made at early proximal tubular sites during alterations in flow through the loop of Henle to elicit the feedback response. Renal blood flow in the 10 isolated kidneys averaged 4 ml/ min-g kidney after an initial vasoconstriction. Filtration rate was 0.52 +/- 0.12 ml/min-g kidney for the period 90–120 min, but progressively fell after 120 min, as did fractional sodium reabsorption and PAH extraction. The feedback regulation of nephron filtration rate was demonstrated during the first 3 hrs of perfusion even with subnormal renal function. The feedback response expressed as the percent reduction of early proximal flow rate when loop of Henle flow was elevated from 0 to 45 nl/min was 41.3 +/- 4.5 (for the first 90 min), 35.3 +/- 7.5 (90-120 min), 24.3 +/- 6.8 (120-150 min), and 26.6 +/- 7.7% (150-180 min). After 180 min, the feedback response was no longer demonstrated. These results show that feedback-induced changes in nephron filtration rate are achieved in the absence of nervous system influences.

Measurement of Single Nephron Filtration Rate in the Kidney of the River Lamprey, Lampetra Fluviatilis L

1978 ◽  
Vol 77 (1) ◽  
pp. 57-69 ◽  
Author(s):  
R. J. MORIARTY ◽  
A. G. LOGAN ◽  
J. C. RANKIN
Keyword(s):  
Filtration Rate ◽  
Gel Filtration ◽  
Reference Substance ◽  
Nephron Filtration Rate ◽  
River Lamprey ◽  
Peritubular Capillaries ◽  
Single Nephron Filtration Rate ◽  
Single Nephron ◽  
51Cr Edta ◽  
Renal Clearances

The reliability of [3H]inulin as a reference substance for the measurement of glomerular filtration rate (GFR) in river lampreys was investigated. Simultaneously measured renal clearances of [3H]inulin and [14C]-polyethylene glycol (PEG) were not significantly different. Recoveries of [3H]inulin in the urine following its injection into the proximal tubule and urinary duct averaged 83.5±4.0% (n = 14) and 93.0±4.6% (n = 9) respectively. No evidence was obtained to suggest penetration of the tubular wall by [3H]inulin following its introduction into peritubular capillaries. Gel-filtration of lamprey plasma and urine produced no signs of any significant degradation of the inulin to fructose. [3H]inulin recoveries, though significantly below 100% (P < 0.001), were considered adequate to justify its use after allowing for possible sources of error. A mean single nephron filtration rate (SNGFR) value of 7.02±0.27 nl/min (n = 89) was obtained from the kidneys of anaesthetized freshwater lampreys. [51Cr]EDTA was found to be totally unsuitable for the measurement of GFR in this species.

Micropuncture method for the determination of nephron filtration rate

1972 ◽  
Vol 333 (3) ◽  
pp. 271-280 ◽  
Author(s):  
J. M. Davis ◽  
J. Schnermann ◽  
M. Horster
Keyword(s):  
Filtration Rate ◽  
Nephron Filtration Rate

Determinants of proximal tubular reabsorption as mechanisms of glomerulotubular balance

1978 ◽  
Vol 235 (2) ◽  
pp. F142-F150 ◽  
Author(s):  
B. J. Tucker ◽  
R. C. Blantz
Keyword(s):  
Proximal Tubule ◽  
Filtration Rate ◽  
Oncotic Pressure ◽  
Peritubular Capillary ◽  
Nephron Filtration Rate ◽  
Vein Occlusion ◽  
Proximal Tubular ◽  
Range Of Values ◽  
Proximal Tubular Reabsorption ◽  
Glomerulotubular Balance

The determinants of absolute proximal reabsorption (APR) were studied in four groups of rats during hydropenia, partial renal vein occlusion (RVO), saline expansion, and RVO after saline expansion. Nephron filtration rate (SNGFR), nephron plasma flow (RPF), APR, and proximal tubule (Pt) peritubular capillary (HPc), and interstitial (HPi) hydrostatic pressures were measured by micropuncture techniques. Subcapsular space (pii) and star peritubular capillary (piE) oncotic pressures were also determined. The peritubular capillary permeability coefficiency (LpAR) and the corresponding effective reabsorptive pressure (ERP) were computed, where APR = LpAR . ERP, and ERP = net reabsorptive pressure across the peritubular capillary. The results indicate that APR correlates best with SNGFR (P less than 0.05), but not with (pii - HPi), RPF, or LpAR. There was a significant relationship between piE and LpAR, where LpAR fell with increases in piE (P less than 0.01). In conclusion, 1) changes in absolute proximal reabsorption correlate best with changes in nephron filtration rate but not with (pii - HPi) across this range of values, 2) changes in efferent oncotic pressure (piiE) correlated inversely with LpAR, and 3) glomerulotubular balance in the proximal tubule can be partially attributed to intraluminal factors.

Nephron filtration rate in conscious rats recovering from anesthesia

1977 ◽  
Vol 232 (4) ◽  
pp. F329-F334
Author(s):  
J. P. Bonvalet ◽  
M. Champion ◽  
F. Wanstok ◽  
G. Berjal
Keyword(s):  
Glomerular Filtration Rate ◽  
Glomerular Filtration ◽  
Filtration Rate ◽  
Experimental Conditions ◽  
Nephron Filtration Rate ◽  
Conscious Rats ◽  
Anesthetized Rats ◽  
Saline Loading ◽  
Single Nephron ◽  
Infusion Technique

Single-nephron glomerular filtration rate (SNGFR) of superficial (S) and juxtamedullary (JM) nephrons was measured in conscious rats with a [14C]ferrocyanide infusion technique. Experiments were carried out in nondiuretic (ND), salt-loaded (SL), and hemorrhagic hypotensive (HH) rats. Mean SNGFR values of S and JM nephrons were 48.7 +/- 4.5 SE and 61.7 +/- 4.2 in ND, 73.6 +/- 8.7 and 87.5 +/- 10.8 in SL, and 29.9 +/- 5.9 and 36.4 +/- 7.1 in HH rats. These values are higher than the values reported in anesthetized rats. The S-to-JM SNGFR ratio was not significantly different in the three experimental conditions (ND, 0.788 +/- 0.032; SL, 0.843 +/- 0.018; and HH, 0.824 +/- 0.030), and did not differ from the values reported in anesthetized rats in similar experimental conditions. It is concluded that anesthesia exerts a depressive effect on GFR, but does not modify intrarenal SNGFR distribution. Neither saline loading nor hemorrhagic hypotension induces SNGFR intrarenal redistribution in conscious rats.

Measurement of nephron filtration in the dog: role of proximal intratubular pressure

1981 ◽  
Vol 241 (3) ◽  
pp. F238-F243
Author(s):  
D. A. Hartupee ◽  
A. H. Gillies ◽  
F. G. Knox
Keyword(s):  
Proximal Tubule ◽  
Filtration Rate ◽  
Free Flow ◽  
Nephron Filtration Rate ◽  
Intratubular Pressure ◽  
Single Nephron Filtration Rate ◽  
Single Nephron ◽  
Proximal Tubular ◽  
Pressure Controlled

Previous studies concerning the measurement of single nephron filtration rate have shown that collections of proximal tubular fluid, in which an oil drop is held in a constant position, do not affect intratubular pressure in the early proximal tubule in the hydropenic rat. Since intratubular pressures are higher in the dog than the rat, we investigated the effect of position-controlled collections on proximal pressure and single nephron filtration rate (SNGFR) in the dog. During position-controlled collections, early proximal pressure fell 5.8 +/- 0.9 mmHg and SNGFR was 76.3 +/- 5.3 nl/min. During proximal re-collections, in which proximal pressure was maintained near the free-flow value using a long immobile oil block, SNGFR was significantly less, 44.4 +/- 5.5 nl/min. For each micropunctured kidney, SNGFR was also estimated by dividing GFR by the number of glomeruli (mean, 5.4 +/- 0.5 X 10(5)). Estimated SNGFR (50.9 +/- 6.3 nl/min) was not significantly different from pressure-controlled SNGFR but was significantly less than position-controlled SNGFR. Accordingly, in the dog, early proximal pressure decreases during position-controlled collection of proximal tubular fluid, resulting in an overestimation of SNGFR. This artifact can be avoided by controlling the intratubular pressure during collection of tubular fluid.

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