1.Anion channel in basolateral cortical membranes of the rabbit kidney.
Pahlavan P1, Mejicano G, Ruiz OS, Arruda JA. Miner Electrolyte Metab. 1992;18(6):386-91.
The presence of chloride conductance in basolateral membranes of proximal tubule is controversial. We measured 36Cl uptake in basolateral membranes loaded with KCl and suspended in a K(+)-free solution to create a positive intravesicular potential difference. Under these conditions, 36Cl uptake was maximal at 1 min, remained stable for at least 10 min and decreased to equilibrium levels by 60-120 min. Collapse of the voltage by valinomycin decreased 36Cl uptake by 46%, indicating the presence of K(+)-gradient-dependent chloride uptake. The chloride channel inhibitor diphenylamine-2-carboxylic acid inhibited 36Cl uptake in a dose-dependent fashion. 36Cl uptake was inhibited equally by unlabeled chloride, iodide and nitrate but not by sulfate or gluconate, indicating that the basolateral anion conductance is relatively selective. 36Cl uptake was pH independent but was calcium dependent. Phosphorylation of basolateral membranes with ATP significantly decreased 36Cl uptake, but the inhibitory effect of ATP was not further altered by exogenous cyclic AMP or the active phorbol ester PMA.
2.Analysis of sucrose esters--insecticides from the surface of tobacco plant leaves.
Simonovska B1, Srbinoska M, Vovk I. J Chromatogr A. 2006 Sep 15;1127(1-2):273-7. Epub 2006 Jul 3.
Sucrose esters from the surface of leaves of Nicotiana tabacum L. have been shown to possess interesting biological activities. We developed a simple and effective method for their analysis using HPTLC silica gel plates, n-hexane-ethyl acetate (1:3, v/v) as developing solvent and aniline-diphenylamine as a detection reagent. Off-line TLC-MS was also used for the detection and identification of the compounds. Solutions containing sucrose esters upon alkaline hydrolysis give sucrose, which is used for indirect estimation by TLC of the sucrose ester content. The method is applicable for the screening for sucrose esters in plant extracts. The extract obtained from the surface of green leaves of oriental tobacco type Prilep P-23 contains sucrose esters and is effective against Myzus persicae (Sulzer) in laboratory and field experiments.
3.Chloride currents activated by calcitonin and cAMP in primary cultures of rabbit distal convoluted tubule.
Tauc M1, Bidet M, Poujeol P. J Membr Biol. 1996 Apr;150(3):255-73.
Chloride (Cl-) conductances were studied in primary cultures of the bright part of rabbit distal convoluted tubule (DCTb) by the whole cell patch clamp technique. The bath solution (33 degrees C) contained (in mM): 140 NaCl, 1 CaCl2, 10 N-2-hydroxy-ethylpiperazine-N'-2-ethanesulfonic acid (HEPES), pH 7.4 and the pipette solution 140 N-methyl-D-glucamine (NMDG)-Cl, 5 MgATP, 1 ethylene-glycol-bis(b-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA), 10 HEPES, pH 7.4. We identified a Cl- current activated by 10(-5) M forskolin, 10(-3) M 8-bromo adenosine 3',5'-cyclic monophophosphate (8 Br-cAMP), 10(-6) M phorbol 12-myristate 13-acetate (PMA), 10(-3) M intracellular adenosine 3',5'-cyclic monophophosphate (cAMP) and 10(-7) M calcitonin. The current-voltage relationship was linear and the relative ion selectivity was Br- > Cl- > > I- > glutamate. This current was inhibited by 10(-3) M diphenylamine-2-carboxylate (DPC) and 10(-4) M 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB) and was insensitive to 10(-3) M 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS).
4.Indirect evidence for the presence of non-specific anion channels in rabbit mandibular salivary gland acinar cells.
Brown PD1, Elliott AC, Lau KR. J Physiol. 1989 Jul;414:415-31.
1. Intracellular pH (pHi) was measured using the fluorescent pH-sensitive dye 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein in acini isolated from the rabbit mandibular salivary gland. 2. Stimulation of the acinar cells with acetylcholine (ACh) evoked an intracellular acidosis, the size of which was dependent on the HCO3-concentration in the bathing medium. A half-maximal acidosis was observed at approximately 10 mM-HCO3-. ACh also evoked an acidosis in HCO3(-)-free solutions containing acetate; a half-maximal acidosis was observed at about 10 mM-acetate. 3. Propionate, lactate and butyrate were also able to support the ACh-evoked acidosis to varying extents. In contrast, formate, pyruvate and salicylate did not support the ACh-induced acidosis to any great extent. 4. Acetazolamide greatly reduced the size of the acidosis in HCO3(-)-buffered medium, but had no effect in acetate-buffered medium, suggesting that the inhibitory effect of acetazolamide was due to a specific inhibition of carbonic anhydrase activity.