While, under low dose of cadmium chloride, mild to moderate changes in hepatocytes around blood vessels in liver, reduction in thickness of epithelium and muscular layer in gizzard; and slight alterations in arrangement of tubules of
loop of henle in the kidney of proximal convoluted tubules with granular cytoplasm were observed.
As the filtrate descends into the medullary region in the descending
loop of Henle, another ten percent of original filtrate volume is reabsorbed as the hyperosmolality of the medulla provides a steep concentration gradient and "sucks" water out.
Incomplete Na+ absorption in thick ascending
loop of Henle results in raised level of PGE2 that further aggravates primary defect of Cl- transport in the thick ascending
loop of Henle.
By working in the ascending
loop of Henle in the kidneys, these diuretics inhibit the reabsorption of sodium, chloride, and water; this results in excretion of sodium, chloride, water, and potassium, as well as some excretion of magnesium and calcium (Aschenbrenner & Venable, 2009).
The segments of primary interest in sodium, chloride and water reabsorption are the proximal tubule, the
loop of Henle, the late distal tubule, and the collecting ducts, as shown in Figure 2.
Calcium phosphate in trace amounts is common, as brushite is supersaturated at the higher pH and filtrate concentration usually occurring at the
loop of Henle, and crystals formed may act as heterogeneous nuclei for calcium oxalate stones [5].
The marginal cells of the stria vascularis contain a similar rich amount of mitochondria as the tubular cells of the proximal
loop of Henle. (8)
This conservation of body water was refined in the mammalian kidneys with the
loop of Henle, which is a countercurrent mechanism to further concentrate urine and conserve body water.
Table 1 Permeability of the Nephron Segments Segment Water NaCl Urea Proximal tubule Yes Yes No
Loop of Henle - Descending limb Yes Slight Slight
Loop of Henle - Thin ascending limb No Yes Slight
Loop of Henle - Thick ascending limb No Slight No Distal tubule and cortical collecting duct * No Slight No Medullary collecting duct * Slight Slight Slight ** Note: * When vasopressin is present, these segments become highly permeable to water allowing a concentrated urine to be excreted.
The thick ascending limb of the
loop of Henle is the principle site of magnesium reabsorption, where 50%-65% of the filtered load is reabsorbed.
The tubular system has four components: (a) proximal tubule (PT), (b)
loop of Henle, (c) distal tubule (DT), and (d) collecting tubule.
