Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We assessed the effects of antidiuretic hormone and cyclic adenosine monophosphate (cAMP) analogues on transepithelial voltage, Ve, and/or net chloride absorption in isolated mouse medullary (mTALH) and cortical (cTALH) thick ascending limbs of Henle; the passive NaCl permeability characteristics and electrical properties of the mTALH; and the effects of anion and cation substitutions and transport inhibitors on both basal and ADH-stimulated Ve and/or net chloride absorption in the mTALH. The data demonstrate that these two segments are functionally heterogeneous: ADH, at concentrations comparable to plasma levels seen in mammalian species during ordinary antidiuresis, and/or cAMP increase three- to fourfold the rate of NaCl absorption in the mTALH but not in the cTALH. The ion substitution and inhibitor data are consistent with the view that NaCl absorption in the mTALH depends on a secondary active transport process: NaCl entry across luminal membranes is a coupled process of indeterminate stoichiometry that is driven by the transmembrane electrochemical gradient for Na+, which is maintained by Na+-K+-ATPase. Finally, the data demonstrate that the mTALH is electrically leaky whether measured electrically, 11 omega . cm2, or isotopically, 50 omega . cm2, but essentially water impermeable; and that the mTALH is perm-selective for Na+ with respect to Cl-. The disparity between electrical resistances measured directly with respect to those calculated from tracer fluxes, together with the hybrid characteristics of mTALH junctional complexes (leaky to Na+ and Cl-; tight to water), may be reconciled by assuming that mTALH junctional complexes contain passive ion permeation pathways composed of narrow channels through which ions pass in single-file fashion.
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PMID:NaCl transport in mouse medullary thick ascending limbs. I. Functional nephron heterogeneity and ADH-stimulated NaCl cotransport. 731 65

Sorbitol and mannitol, two stereoisomeric osmolytes, inhibit the ATP-dependent Ca2+ transport in inside-out vesicles derived from basolateral membranes from kidney proximal tubules. This inhibition (I0.5 = 400 and 390 mM respectively) cannot be attributed to an increase in Ca2+ permeability, since the rate of EGTA-stimulated Ca2+ efflux from preloaded vesicles is not modified by these osmolytes. In the presence of 1 M sorbitol or mannitol, Ca2+ uptake is inhibited by 70 and 75%, respectively. Since the Ca(2+)-stimulated ATPase activity is unaffected, sorbitol and mannitol uncouple the Ca2+ transport from the ATPase activity. The inhibition of Ca2+ transport by these osmolytes is reversible, since the inhibition disappears when the vesicles are preincubated with 1 M sorbitol or mannitol and then diluted 25-fold in reaction medium to measure Ca2+ accumulation. On the other hand, these osmolytes protect the (Ca2+ + Mg2+) ATPase from the inhibition of Ca2+ transport and ATPase activity by urea and guanidinium. These data suggest that the high concentrations of polyols that renal cells accumulate during antidiuresis, may regulate Ca2+ transport across the plasma membrane. In addition, polyols may protect the (Ca2+ + Mg2+) ATPase from the deleterious structural effects of urea, a compound that also accumulates during antidiuresis.
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PMID:Polyols that accumulate in renal tissue uncouple the plasma membrane calcium pump and counteract the inhibition by urea and guanidine hydrochloride. 770 12

The effect of crude extract of roots of Bredemeyera floribunda Willd., Polygalaceae used by Brazilian popular medicine as a potent diuretic, on renal function in antidiuresis or water diuresis in rats, was studied. During intravenous infusion of the extract (0.05 mg/min/100 g), mean arterial pressure did not change significantly but urine flow, glomerular filtration rate, fractional water and sodium excretion and solute clearance increased significantly, in both groups of animals. In antidiuresis rats the extract significantly increased reabsorption of water by the collecting duct and in water diuresis animals the extract significantly increased free water clearance. Our findings indicate a direct effect of extract on glomerular filtration rate, possibly by detergent like interactions with structural components of glomerular membranes and/or by decreasing renal perfusion pressure. The study on the concentrating and diluting mechanisms suggests preferential action of extract in the proximal tubular cells, possibly on the (Na(+)-K+)-ATPase countertransport system and/or on other proteins components of tubular cell membranes involved with salt transport mechanisms.
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PMID:Effect of crude extract of roots of Bredemeyera floribunda Willd. II. Effect on glomerular filtration rate and renal tubular function of rats. 799 Apr 95