Kidneys operation

The efficiency of an eliminating organ in removing drug from plasma depends on the health of the organ. Thus, diseased kidneys operate less efficiently, and the net change in clearance is proportional to the extent of renal impairment. 

The kidney operates reversibly, and minimum work implies Sgen = 0. 

The kidney operates reversibly, and minimum work implies = 0. Subtracting T times the entropy balance form the energy balance gives... 

Certain cells and organs (e.g., kidneys) operate to prevent hyperkalemia by removing potassium from the blood after a meal. 

Ammonia is an exceptional chemical in that it is manufactured in the renal tubular cells and excreted into the urine. For most other chemicals, the kidney operates by transferring them in one direction or the other between the tubular and peritubular fluids but without itself manufacturing the chemicals. The ammonia produced in the tubular cells is derived from glutamine, as already described. The other chemicals yielded by the splitting of ammonia from glutamine are neither acids nor alkalis this mechanism provides the kidney with a source of base which can be produced without incurring other acid -base alterations. 

Wet spinning of this type of hoUow fiber is a weU-developed technology, especiaUy in the preparation of dialysis membranes for use in artificial kidneys. Systems that spin more than 100 fibers simultaneously on an around-the-clock basis are in operation. Wet-spun fibers are also used widely in ultrafiltration appUcations, in which the feed solution is forced down the bore of the fiber. Nitto, Asahi, Microgon, and Romicon aU produce this type of fiber, generaUy with diameters of 1—3 mm. 

Factors controlling calcium homeostasis are calcitonin, parathyroid hormone(PTH), and a vitamin D metabolite. Calcitonin, a polypeptide of 32 amino acid residues, mol wt - SGOO, is synthesized by the thyroid gland. Release is stimulated by small increases in blood Ca " concentration. The sites of action of calcitonin are the bones and kidneys. Calcitonin increases bone calcification, thereby inhibiting resorption. In the kidney, it inhibits Ca " reabsorption and increases Ca " excretion in urine. Calcitonin operates via a cyclic adenosine monophosphate (cAMP) mechanism. 

The method of choice for the determination of a- and P-endosulfan in blood, urine, liver, kidney, brain, and adipose tissue is gas chromatography equipped with an electron capture detector (GC/ECD) (Coutselinis et al. 1976 Demeter and Heyndrickx 1979 Demeter et al. 1977 Le Bel and Williams 1986). This is because GC/ECD is relatively inexpensive, simple to operate, and offers a high sensitivity for halogens (Griffith and Blanke 1974). After fractionation of adipose tissue extracts using gel permeation chromatography, detection limits of low-ppb (1.2 ng/g) were achieved for endosulfan and other chlorinated pesticides using GC/ECD (Le Bel and Williams 1986). 

Meanwhile we have shown that the excision activation of ICOR channels is due to disinhibition [72]. The respective inhibitor, operationally named cytosolic inhibitor (Cl), is present in the cytosol of placenta trophoblast cells HT29- and Tg4-colonic carcinoma cells and RE cells of normal and CF patients. The molecule has an apparent molecular weight of 700-1 500 Da it is amphiphilic heat stable and not digested by trypsin, proteases, nucleotidases, lipases or amylase [72]. Burc-khardt, Fromter and their collaborators [114] have confirmed our results and extracted a similar or identical Cl from kidney cortex. 

There are also Na+ pump y-subunits, a family of=15 kDa proteolipids that can associate with sodium pump a-subunits. However they are not necessary for pump activity nor are they expressed in all cells. The y-subunits are classed as members of the FXYD gene family and several are expressed in brain [5]. The kidney expresses almost exclusively Na+,K+ pumps with arsubunits throughout the functionally diverse segments of the nephron, but different y-subunits are expressed in different segments. From this it is inferred that different y-subunits optimize the sodium pump for operation under the varying ionic environments [6]. 

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