The identity of interstitial fluid and hilar lymph in the kidney

Intraarterial Doxorubicin Infusion Treatment with and without Occlusion of the Renal Artery in Rabbit Renal VX-2 Carcinoma

The aim of this investigation was to establish an animal model for studying fractionated intraarterial treatment of a rabbit kidney VX-2 carcinoma. As repeated catheterizations and drug infusions may cause vascular lesions, we wanted to find whether the rabbit renal artery could be catheterized several times within a short period of time with acceptable iatrogenic vascular trauma. Each of 3 groups of rabbits with implanted renal VX-2 carcinoma were treated 3 times with either 1) temporary renal artery occlusion combined with infusion (occlusion infusion) of a) physiologic saline (OIS) or b) doxorubicin (OID), or 2) with renal artery infusion of doxorubicin. OID was administered in 20 of 21 attempts, OIS in 21 of 24, and infusion of doxorubicin in 20 of 21 attempts. Renal arterial spasm was seen in 5 of 22 rabbits, rarely at the first catheterization, more frequently during the second and third. Permanent iatrogenic vascular trauma occurred in 4 of 15 rabbits after the second and third occlusion infusion. We conclude that the rabbit kidney with implanted VX-2 carcinoma may be a useful model for testing fractionation schemes for multiple intraarterial infusions of antineoplastic drugs.

The renal cortical lymphatic system in the rat, hamster, and rabbit

Rat, hamster, and rabbit renal cortical lymphatics were examined by light and electron microscopy. Rat and hamster kidneys possessed both intra- and interlobular lymphatics that were structurally similar at the light microscopic level. Ultrastructural examination of the hamster lymphatic endothelium, however, revealed an unusual arrangement of cytoplasmic extensions not seen in the other two species. The intralobular lymphatics were related primarily to tubules, afferent arterioles, and renal corpuscles and were consistent with lymph formation from both plasma filtrate and tubular reabsorbate. Interlobular lymphatics were seen in connective tissue associated with the interlobular blood vessels. Rabbit cortex contained only interlobular lymphatics. Cross-sectional area, maximum diameter, volume density, and profile density were determined by stereological measurements using a computer-based image analyzer. The morphological data from the rat were used, in combination with published values for lymph flow, to calculate the rate of lymph formation per unit area of endothelium in lymphatics of the renal cortex. Among kidneys fixed by retrograde perfusion, the cortical lymphatic system was most extensive in maximum diameter, volume density, and profile density. It was smallest in the rabbit and intermediate in the rat. Lower volume and profile density were found for rat kidneys fixed by the dripping technique. It was concluded that: tubular reabsorbate probably contributes to renal lymph in the rat and hamster, but not in the rabbit; significant differences exist in the extent of the renal lymphatic systems among the three species, with the hamster kidney having the richest network and the rabbit the poorest; the method of fixation influences the measured size and density of renal cortical lymphatics; and the estimated rate of lymph formation in the kidney of the rat is roughly comparable to that in the dog.

The extravascular pool of albumin in the non-diuretic rat kidney estimated by means of radioactive tracers and quantitative immunochemistry

The extravascular pool of albumin in the non-diuretic rat kidney was determined as the difference between total and intravascular albumin pools. The total pool of albumin was determined in two ways in the same kideny: 1. as the distribution volume of rat endogenous albumin measured immunochemically and 2. as the distribution volume of 125I-labelled rat albumin equilibrated for 4 days. The distribution volume of 131I human albumin after 1 min equilibration was taken as a measure of the intravascular pool. Total albumin pool estimated as rat endogenous albumin volume of distribution averaged 13.4, 25.1, and 43.0 mul per 100 mg tissue in cortex, outer and inner medulla, respectively. Similar figures were obtained using 125I-labelled rat albumin. Intravascular pool of albumin in the 3 zones averaged 7.2, 19.7, and 26.8 mul per 100 mg tissue. The calculated extravascular fraction of albumin averaged 0.44, 0.21, and 0.35 for cortex, outer and inner medulla, respectively.

Intrarenal distribution of albumin and immunoglobulin M in the non-diuretic-rat

The intrarenal distribution of 125I-immunoglobulin M (125I-IgM) and 131I-albumin was studied in non-diuretic rats. Tracer equilibration times of 1, 10 and 60 min were used. In the 1 min series, in all renal zones (cortex, outer and inner medulla) the albumin volumes did not differ significantly from those of the much larger molecule, IgM. The 1 min values were found to be 9, 6, 17, and 24 mul per 100 mg tissue for whole kidney, cortex, outer and inner medulla, respectively. In the 10 and 60 min series the cortical albumin and IgM volumes did not differ significantly either, while in the medulla the albumin volumes slightly exceeded the IgM volumes. The 10 min values did not differ significantly from the corresponding 1 min values, except that in the cortex the albumin value was higher at 10 than at 1 min. All 60 min values were significantly higher than the corresponding 1 min values. In the medullary zones these differences can be explained for the most part as caused by accumulation of free radioiodide. In the cortex free radioiodide plays a minor role and the 60 min distribution volumes of both proteins (whether corrected for free radioiodide or not) exceed the 1 min volumes by some 50 per cent. The 1 min values can be taken to represent the intravascular compartment; the 60 min values include the extravascular compartment. In conclusion, the present study indicates that: 1. The extravascular pool of albumin constitutes only a minor fraction of the total intrarenal pool-in the cortex about one third. 2. The equilibration of tracer proteins (IgM or albumin) between plasma and the extravascular compartments of the kidney is a rather slow process; the results are compatible with a mean transit time of tracer albumin from plasma to lymph of 26.5 min, as found by others [19]. 3. Extravasation of IgM and albumin most likely takes place via large vescicles or "big leaks".

The intrarenal distribution of 125I-albumin in the Syrian hamster

The intrarenal distribution of radioiodinated human serum albumin (125RISA) after intravenous injection was studied in Syrian hamsters by scintillation counting and frozen section autoradiography. After 15, 30 and 60 min the virtual plasma albumin space in the renal cortex of the hamster represented 6.49, 7.13, and 8.06 percent respectively of the kidney tissue volume. From the cortex to the renal papilla the albumin space increased to about 30 percent of the tissue volume. In comparison to this the albumin space in the renal cortex of the rat was about 20% and in the renal papilla about 33% (11). Frozen section autoradiography indicated that the distribution of radioalbumin in the renal cortex of the Syrian hamster is limited mainly to the kidney vessels, being especially noticeable in the glomerular capillaries. Toward the papilla increasingly greater (mainly extratubular) activity could be observed not only intravascularly but also interstitially. In the cortex of the rat kidney, on the other hand, radioactive albumin was accumulated (probably by filtration and reabsorption) predominantly in the proximal tubular epithelium. Wtithin 30 min thekidneys of the rat excreted mor than 10 times as much 125I than the hamster kidneys. These results (substantially less cortical accumulation and urinary excretion of radioalbumin in the Syrian hamster) indicate that, in contrast to the rat, obviously much less albumin is filtered (and then accumulated by proximal reabsorption) by the Syrian hamster glomeruli. This suggests that the Syrian hamster kidney is more suitable than the rat kidney for determining the interstitial, cortical, albumin space.