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

Abstract

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

Clinicopathologic, histologic, and toxicologic findings in 70 cats inadvertently exposed to pet food contaminated with melamine and cyanuric acid

“…6 In cats, the renal subcapsular veins are large and drain the outer renal cortex. 16 They travel along the exterior surface of the kidney and empty directly into the renal vein, whereas in dogs, these veins travel through the cortex to communicate with the arcuate and interlobular veins. 16 This specialized renal vascular anatomy may make cats less tolerant of acute renomegaly.…”

Microplastics in Internal Tissues of Companion Animals from Urban Environments

“…Indeed, microspheres in circulation can accumulate in the narrower capillaries, causing mechanical blockage, potentiated by particle aggregation [ 38 ], or suffer differential removal by phagocytes or platelet aggregation [ 39 ]. Larger particle sizes may be found in the kidney due to accumulation in the preglomerular afferent arterioles, with a diameter of 18 µm in the dog [ 40 ]. Similarly, in addition to exposure to only a smaller inhalable size (<10 µm), the lung presents a narrow pulmonary capillary network and slower elimination of smaller microplastics [ 41 ], with retention of polystyrene microspheres > 8 µm injected in the pulmonary artery of dogs, being unable to cross the pulmonary capillaries [ 42 ].…”

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“…Angiotensin 11 infused in low doses causes sodium retention and in high doses causes natriuresis and diuresis (Barraclough & Mills, 1965;Laragh & Sealy, 1973;Navar & Longford, 1974). There have been suggestions that angiotensin II has a role as an intrarenal hormone acting on the distal part of the nephron and the renal vasculature (Krahe, Hofbauer & Gross, 1970;Nissen & Galskov, 1972;Itskovitz, Hebert & McGill, 1973;Thurau, 1974;Jackson, Guyton & Hall, 1977;Johns, 1979).…”