Micropuncture Study of Glomerulotubular Balance in the Rat Kidney

Fluid was collected by micropuncture from proximal and distal convolutions of anesthetized rats and analyzed for inulin, sodium, urea, and total osmotically active solute. The proximal fluid/plasma (F/P) sodium ratio was not significantly different from unity in antidiuretic animals, but was as low as 0.78 during mannitol diuresis. The distal F/P sodium ratio averaged 0.62 in antidiuresis, and 0.24 during osmotic diuresis. The data are interpreted to indicate active sodium transport by both proximal and distal convolutions. The F/P ratios for inulin, urea, and total osmotically active solute are in general agreement with previous studies.

Download Full-text

Micropuncture study of uric acid transport in rat kidney

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1975.228.5.1597 ◽

1975 ◽

Vol 228 (5) ◽

pp. 1597-1605 ◽

Cited By ~ 25

Author(s):

RG Abramson ◽

MF Levitt

Keyword(s):

Uric Acid ◽

Proximal Tubule ◽

Rat Kidney ◽

Chromatographic Technique ◽

Acid Transport ◽

Cent Sodium ◽

Micropuncture Study ◽

Nephron Segment ◽

Fluid Collections ◽

Column Chromatographic

Free-flow micropuncture studies were perfromed to evaluated uric acid transport in the rat kidney. In all studies (a-minus 14C) uric acid and (methoxy-3H) inulin wereadministered. A simple two-step, column-chromatographic technique was utilized to separate (2-minus 14C) uric acid from its labeled oxidation product in plasma, urine, and tubular fluid. Tubular fluid collections were obtained from the early-and late-proximal tubule under control conditions and during subsequent volume expansion induced with 0.9 per-cent sodium chloride. These studies indicate bidirectional, possible active, uric acidtransport in the proximal tubule undr control conditions, with net reabsorption evident early and net decretion apparent late in this nephron segment. In association with volumeexpansion net uric acid reabsorption and secretion both decreased. No significant nettransport was evident beyond the accessible portion of the late-proximal tubule in either experimental state.

Download Full-text

Proximal tubular lactate transport in rat kidney: A micropuncture study

Kidney International ◽

10.1038/ki.1974.35 ◽

1974 ◽

Vol 5 (4) ◽

pp. 261-270 ◽

Cited By ~ 27

Author(s):

Bernhard Höhmann ◽

Peter P. Frohnert ◽

Rolf Kinne ◽

Karl Baumann ◽

F. Papavassiliou ◽

...

Keyword(s):

Rat Kidney ◽

Lactate Transport ◽

Micropuncture Study ◽

Proximal Tubular

Download Full-text

Micropuncture study of isolated perfused rat kidney

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1967.212.1.77 ◽

1967 ◽

Vol 212 (1) ◽

pp. 77-82 ◽

Cited By ~ 31

Author(s):

J Bahlmann ◽

G Giebisch ◽

B Ochwadt ◽

W Schoeppe

Keyword(s):

Rat Kidney ◽

Isolated Perfused Rat Kidney ◽

Perfused Rat Kidney ◽

Micropuncture Study

Download Full-text

Micropuncture Study of Pressures in Proximal Tubules and Peritubular Capillaries of the Rat Kidney and Their Relation to Ureteral and Renal Venous Pressures

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1956.185.2.430 ◽

1956 ◽

Vol 185 (2) ◽

pp. 430-439 ◽

Cited By ~ 254

Author(s):

Carl W. Gottschalk ◽

Margaret Mylle

Keyword(s):

Rat Kidney ◽

Venous Pressure ◽

Proximal Tubules ◽

Peritubular Capillary ◽

Pressure Elevation ◽

Intratubular Pressure ◽

Peritubular Capillaries ◽

Micropuncture Study ◽

Capillary Pressures ◽

Hypertonic Dextrose

Methods are described for direct measurement of the hydrostatic pressure in the surface tubules and capillaries of the rat kidney. In fifty-six anesthetized rats intratubular pressure averaged 13.5 ± 2.4 mm Hg. Subsequent microdissection showed that all of the 112 puncture sites so localized were in the first two-thirds of the proximal convoluted tubule. Under all conditions studied, intratubular pressure and the pressure in the peritubular capillaries were approximately the same. Intravenous injection of hypertonic dextrose solution generally produced a brief rise in intratubular and peritubular capillary pressures, which returned to their preinjection levels while the diuresis so produced continued, although at less than the maximal rate. Obstruction of the ureter of kidneys undergoing diuresis resulted in a prompt rise in intratubular pressure, which agreed closely with the simultaneously determined ureteral pressure. Elevation of the ureteral pressure with a pressure bottle had no effect on intratubular or peritubular capillary pressures until it exceeded the pre-existing intratubular and peritubular capillary pressures, and then all rose together up to a maximum intratubular pressure above which elevation of ureteral pressure resulted in no further rise in intratubular or peritubular capillary pressure. Elevation of applied ureteral pressure in kidneys with collapsed tubules and in dead animals did not increase the intratubular pressure, demonstrating that the rise in intratubular pressure produced in this manner in functioning kidneys was not simply a direct back transmission of pressure. Elevation of renal venous pressure by compression of the renal vein also had no effect on intratubular and peritubular capillary pressures until their pre-existing values were exceeded, and then all three pressures rose together.

Download Full-text