Influence of luminal diameter and flow velocity on the isotonic fluid absorption and36Cl permeability of the proximal convolution of the rat kidney

1971 ◽  
Vol 324 (4) ◽  
pp. 288-296 ◽  
Author(s):  
H. W. Radtke ◽  
G. Rumrich ◽  
S. Kl�ss ◽  
K. J. Ullrich
Keyword(s):  
Flow Velocity ◽  
Rat Kidney ◽  
Fluid Absorption ◽  
Luminal Diameter ◽  
Isotonic Fluid ◽  
Proximal Convolution

Dependence of ion fluxes on fluid transport by rat proximal tubule

1986 ◽  
Vol 250 (4) ◽  
pp. F680-F689 ◽  
Author(s):  
K. Bomsztyk ◽  
F. S. Wright
Keyword(s):  
Proximal Tubule ◽  
Fluid Transport ◽  
Rat Kidney ◽  
Water Flux ◽  
Fluid Secretion ◽  
Proximal Convoluted Tubule ◽  
Ion Fluxes ◽  
Fluid Absorption ◽  
Fluid Flux ◽  
K Transport

The effects of changes in transepithelial water flux (Jv) on sodium, chloride, calcium, and potassium transport by the proximal convoluted tubule were examined by applying a microperfusion technique to surface segments in kidneys of anesthetized rats. Perfusion solutions were prepared with ion concentrations similar to those in fluid normally present in the later parts of the proximal tubule. Osmolality of the perfusate was adjusted with mannitol. With no mannitol in the perfusates, net fluid absorption was observed. Addition of increasing amounts of mannitol first reduced Jv to zero and then reversed net fluid flux. At the maximal rates of fluid absorption, net absorption of Na, Cl, Ca, and K was observed. When Jv was reduced to zero, Na, Cl, and Ca absorption were reduced and K entered the lumen. Na, Cl, and Ca secretion occurred in association with the highest rates of net fluid secretion. The lumen-positive transepithelial potential progressively increased as the net fluid flux was reduced to zero and then reversed. The results demonstrate that changes in net water flux can affect Na, Cl, Ca, and K transport by the proximal convoluted tubule of the rat kidney. These changes in net ion fluxes are not entirely accounted for by changes in bulk-phase transepithelial electrochemical gradients.

Isotonic Fluid Absorption during Hysteroscopy Resulting in Severe Hyperchloremic Acidosis

2005 ◽  
Vol 103 (1) ◽  
pp. 203-204 ◽  
Author(s):  
Monika Schäfer ◽  
Britta S. Von Ungern-Sternberg ◽  
Edward Wight ◽  
Markus C. Schneider
Keyword(s):  
Fluid Absorption ◽  
Hyperchloremic Acidosis ◽  
Isotonic Fluid

Pulmonary microcirculatory response to localized hypercapnia

1982 ◽  
Vol 53 (6) ◽  
pp. 1556-1564 ◽  
Author(s):  
T. Koyama ◽  
M. Horimoto
Keyword(s):  
Flow Velocity ◽  
Time Course ◽  
Capillary Flow ◽  
Mean Flow ◽  
Velocity Change ◽  
Luminal Diameter ◽  
Initial Values ◽  
Pulmonary Capillary ◽  
Before And After ◽  
Pulmonary Microvessels

Anesthetized bullfrogs were examined to study the effects of localized hypercapnia on the red blood cell (RBC) velocity in pulmonary alveolar microvessels on the exposed lung surface. Before and after the exposure of a small area of the lung surface 6 mm in diameter to a hypercapnic gas mixture, the region was exposed to CO2-free control gas. The RBC velocity was measured by the use of a laser Doppler microscope. Both mean flow velocity (MV) and pulsatile amplitude (PA) were determined from the resulting flow velocity contour. Responses of pulmonary microvessels to hypercapnia were examined by measuring the vessel diameters with an ocular microscale of the microscope while gas mixtures were applied to a 1-mm-diameter region of the surface. During hypercapnia both MV (2.31 +/- 0.27 mm/s) and PA (0.54 +/- 0.15 mm/s) in the alveolar arterioles (luminal diameter = 64 +/- 14 microns) were reduced, each reaching a minimum (2.01 +/- 0.24 and 0.43 +/- 0.19 mm/s, respectively) prior to gradual returns to their initial values. After reintroduction of the control gas, the values of MV and PA approached initial values more rapidly. In capillaries MV (1.44 +/- 0.18 mm/s) and PA (0.28 +/- 0.06 mm/s) decreased to 1.25 +/- 0.10 and 0.15 +/- 0.05 mm/s, respectively. The maximum reduction of PA (-44.6%) therefore clearly exceeded that of MV (-12.4%) in capillary flow. An analog model calculation suggested that the reduction in diameter of the arteriolar system could reduce PA more than MV in the pulmonary capillary network. The time course of the velocity change closely resembled that of the diameter change in relatively large arterioles. Vasoconstriction of the arterioles therefore appeared to be the major cause of these decrements in MV and PA.

Autoregulation in vasa recta of the rat kidney

1983 ◽  
Vol 245 (1) ◽  
pp. F32-F40 ◽  
Author(s):  
H. J. Cohen ◽  
D. J. Marsh ◽  
B. Kayser
Keyword(s):  
Blood Flow ◽  
Arterial Pressure ◽  
Flow Velocity ◽  
Volume Expansion ◽  
Collecting Duct ◽  
Rat Kidney ◽  
Extracellular Fluid ◽  
Vessel Diameter ◽  
Video Adaptation ◽  
Vasa Recta

Vasa recta blood flow autoregulation was studied by measuring flow velocity in individual vessels on the papilla surface with a video adaptation of the dual-slit erythrocyte velocity method. Vessel diameter did not vary with arterial pressure in the range of 60-150 mmHg, allowing the calculation of the ratio of flows in a single vessel at two pressures from the ratio of velocities. Flow velocity in single vasa recta increased with arterial pressure to 75 mmHg, remained constant in the range of 75-125 mmHg, and increased with higher pressures. In a second series of animals, whole kidney blood flow auto-regulated above 90 mmHg. Vasa recta and whole kidney flow patterns were not changed by extracellular fluid volume expansion. Volume expansion caused a greater increase in ascending than in descending vasa recta flow, reflecting the volume load from enhanced collecting duct reabsorption in diuresis. In a final series, Na excretion varied with arterial pressure in the range of 90-130 mmHg. Because vasa recta velocity remains constant within this range, pressure diuresis cannot be caused by the lack of autoregulation of vasa recta blood flow, at least to 130 mmHg.

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