The Magnitude of the Skimming Phenomenon in the Interlobular Arteries of the Cat Kidney

Acta Physiologica Scandinavica

1968

NISSEN, O. 1. The extraction fraction of p-aminohippurate m the superficial and deep venous drainage area of the cat kidney. Acta physiol. scand. 1968. 73. 329-338.At plasma concentrations below 40 p.g/ml the average extraction fraction of PAH was 0.95 in the superficial drainage area (consisting of approximately the outer half of the cortex), and 0.82 in the deep drainage area (the inner cortex + the medulla). Loading with Ringer's fluid, mannitol solution or plasma generally resulted in a decrease in the extraction fraction of both areas. The two extraction fractions fell to 0.86 and 0.64, respectively. The incompleteness of the extraction cannot be attributed to admixture of blood from the fibrous and fatty capsules of the kidney or to impurities in the PAH preparations. The erythrocytes showed a very low permeability to PAH; correction of renal venous plasma concentrations for diffusion of PAH from erythrocytes to plasma is unnecessary in the cat.-The Reubi principle of calculating the medullary plasma flow as the difference between the total renal plasma flow and the clearance of PAH is misleading in the cat, as it presumes complete extraction in cortical tissue.

mentioning

confidence: 93%

mentioning

confidence: 99%

The Extraction Fraction of p-Aminohippurate in the Superficial and Deep Venous Drainage Area of the Cat Kidney

Acta Physiologica Scandinavica

1968

“…In a previous paper (Nissen 1965) the occurrence of different plasma protein concentrations in blood samples obtained from the subcapsular veins (by puncture) and the deep veins (by catheterization) of the cat kidney has been reported. The concentrations were respectively 9 per cent higher and 11 per cent lower than the concentration of arterial blood taken simultaneously.…”

mentioning

confidence: 96%

The Filtration Fractions of Plasma Supplying the Superficial and Deep Venous Drainage Area of the Gat Kidney

Acta Physiologica Scandinavica

1966

Self Cite

NISSEN, 0. I. The filtration fractions of plasma supplying the superjcial and deep venous drainage area of the cat kidney. Acta physiol. scand. 1966. 68. 275-285. In 23 expts. the plaema.concentrations of protein and inulin were measured in blood collected simultaneously from a n artery, from the subcapsular, and from the deep veins of the cat kidney. These concentrations allow a calculation of the filtration fractions of the plasma flows supplyidg, partly the superficial cortex and partly the deep cortex plus medulla. A filtration fraction averaging 0.34 was found for the plasma supplying the superficial cortex. The filtration fraction of the plasma, supplying the deep cortex and the medulla was lower; the ratio: filtration fraction in deep area/ filtration fraction in superficial area (FFn/FFs) was usually 0.70 to 0.95 and the average (0.85) was significantly lower than 1.00 ( p < 0.001). The existence in the deep parts of the kidney of various vessels through which the plasma (blood) may by-pass the capillary tufts of juxtamedullary glomeruli provides the possibility of accounting for the observed deviation of FFD/FFs from 1,00 without resorting to the assumption of (basically) different filtration fractions for plasma entering glomerular tufts in deep and superficial glomeruli. A by-pass of a magnitude sufficient to account for the deviation may also account for a medullary plasma flow as reported by others.

“…• In the cat kidney, the veins draining the outer cortex are well separated from those draining the inner cortex and the medulla, because the blood from the outer cortex leaves through subcapsular veins which do not join the arcuate vein system until the hilar region (1,2) (Fig. 1).…”

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confidence: 99%

“…Vibe art -Vrhi--, (1) and that the same amount of protein enters and leaves the area per unit of time,…”

mentioning

confidence: 99%

Direct Measurement of Superficial and Deep Venous Flow in the Cat Kidney

Galskov

1972

Circulation Research

Self Cite

In an excised cat kidney, the subcapsular veins were clipped near their connections with the renal vein and cut open distal to the clamps. The kidney was then placed in an oil-filled lucite chamber and perfused from a donor cat via tubes entering the chamber through its close-fitting lid. The blood leaking from the cut subcapsular veins was led to one flowmeter; that leaving via the cannulated renal vein (supplied now only by the arcuate vein system) was led to another flowmeter. Catecholamines and stimulation of the renal nerves reduced the arcuate blood flow more than the subcapsular blood flow, the two average reductions being 28% and 20% with epinephrine and 22% and 14% with stimulation of the renal nerves. Angiotensin reduced both flows equally. Microspheres reduced the subcapsular flow more than the arcuate flow, the two average reductions being 42% and 25% of the control flows. This effect was probably caused by trapping of the microspheres in the distal ends of the interlobular arteries beyond the inlets to the afferent arterioles, since these vessels are too narrow to allow free entrance of the microspheres. The preferential effect of epinephrine and nerve stimulation on the deep circulation is thought to be the result of the special structure of the juxtamedullary glomerular units. • In the cat kidney, the veins draining the outer cortex are well separated from those draining the inner cortex and the medulla, because the blood from the outer cortex leaves through subcapsular veins which do not join the arcuate vein system until the hilar region (1, 2) (Fig. 1). In this paper, we will describe how the rates of blood flow leaving the subcapsular and the arcuate veins can be measured directly and simultaneously and show that the vessels in the two drainage areas react differently to certain external