Hydronephrosis: A new method to visualize vas afferens, efferens, and glomerular network

Abstract

We have developed a new preparation for in vivo visualization of the glomerular microcirculation, the vas afferens and the vas efferens. This preparation utilizes postischemic hydronephrosis (PIH) to destroy the renal tubular system while preserving a portion of the cortex. In this preparation, glomeruli and associated vasculature remained intact. Observations can be made with either incident light or transillumination. The inner diameter of the vas afferens, measured within 50 microns of the glomerular vascular pole, was 7.9 +/- 0.5 microns (N = 12; SEM) while that of the vas efferens was 7.7 +/- 0.5 microns (N = 12). Both vessels were narrower adjacent to the glomerulus; minimal diameters in this region were 4.5 +/- 0.5 microns (N = 10) and 4.3 +/- 0.5 microns (N = 11), respectively. A specialized round cell, which may act as a sphincter, was seen in the vas efferens. In a second series of experiments, blood velocity was measured in the vas afferens and efferens about 100 microns from the vascular pole. Mean control velocities at these sites were 5.9 +/- 0.9 (N = 14) and 4.6 +/- 1.3 (N = 9) mm X sec-1, respectively; diameters at these same sites were 10.3 +/- 0.6 microns and 11.2 +/- 0.7. During angiotensin II infusion (first series, 0.2 to 0.4 micrograms X min-1 X kg-1, i.v.) the vas efferens in the vicinity of the glomerulus constricted by 22% whereas the corresponding vas afferens showed no consistent response. During angiotensin II infusion, the filtration fraction (GFR/RPF) may, therefore, be elevated by an increased resistance in the vas efferens, particularly at the outflow point of the glomerulus. In the second series of experiments higher dosages of angiotensin II caused vasoconstriction of both vessels, especially at sites more distant from the glomerulus. Furthermore, the new approach is suitable for observing the flow direction within single capillaries of one third to one half of the glomerulus. Therefore, for the first time it is possible to determine the real flow direction in a three-dimensional way.

Leukocyte Recruitment to the Inflamed Glomerulus: A Critical Role for Platelet-Derived P-Selectin in the Absence of Rolling

“…To achieve this aim, we made use of the technique of renal hydronephrosis. This approach overcomes the difficulty of visualizing structures deep in the renal cortex by eliminating much of the renal medulla and rendering the remaining cortex transparent, while maintaining glomerular perfusion (25). Direct visualization of glomeruli in these experiments has demonstrated that leukocyte recruitment to the glomerulus occurs via a novel pathway involving overlapping roles for the ␤ 2 -integrin/ICAM-1 pathway, P-selectin, and platelets in the absence of detectable rolling in glomerular capillaries.…”

“…To visualize the glomerular microvasculature, we used the technique of hydronephrosis (13,25,48,49). Given the possibility that the process of hydronephrosis may have impacted upon glomerular function, we examined various parameters to assess the inflammatory response in glomeruli of hydronephrotic kidneys.…”

The impaired renal vasodilator response attributed to endothelium-derived hyperpolarizing factor in streptozotocin - induced diabetic rats is restored by 5-methyltetrahydrofolate

“…The techniques for induction of hydronephrosis and preparation of the hydronephrotic kidney have been described in detail previously [20,21]. In brief, after anaesthesia with halothane (Fluothane, Zeneca, Destelbergen, Belgium) a unilateral hydronephrosis was induced by a permanent ligation of the left ureter.…”

Cellular mechanisms mediating rat renal microvascular constriction by angiotensin II.

“…The right ureter was exposed by a small abdominal incision and ligated under ether anesthesia (Showa Chemicals, Tokyo, Japan). 8-10 wk after the surgery, renal tubular atrophy had progressed to a stage that allowed direct microscopic visualization of renal microvessels (20). At this point, the kidneys were excised and studied.…”