ISSN:
1432-1424
Keywords:
Key words: Inner medullary collecting duct — mIMCD-3 cell-line — Whole cell configuration — Patch Clamp — Chloride conductance — CFTR — Chloride secretion
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Abstract. The chloride conductance of inner medullary collecting duct cells (mIMCD-3 cell line) has been investigated using the whole cell configuration of the patch clamp technique. Seventy-seven percent of cells were chloride selective when measured with a NaCl-rich bathing solution and a TEACl-rich pipette solution. Seventy-five percent of chloride-selective cells (90/144) had whole cell currents which exhibited an outwardly-rectifying (OR) current-voltage (I/V) relationship, while the remaining cells exhibited a linear (L) I/V relationship. The properties of the OR and L chloride currents were distinct. OR currents (mean current densities at ±60 mV of 66 ± 5 pA/pF and 44 ± 3 pA/pF), were time- and voltage-independent with an anion selectivity (from calculated permeability ratios) of SCN− (2.3), NO− 3 (1.8), ClO− 4 (1.7), Br− (1.7), I− (1.6), Cl− (1.0), HCO− 3 (0.5), gluconate− (0.2). Bath additions of NPPB, flufenamate, glibenclamide (all 100 μm) and DIDS (500 μm) produced varying degrees of block of OR currents with NPPB being the most potent (IC50 of approximately 50 μm) while DIDS was the least effective. Linear chloride currents had similar current densities to the OR chloride currents and were also time- and voltage-independent. The anion selectivity sequence was SCN− (2.5), NO− 3 (1.9), Br− (1.4), I− (1.1), Cl− (1.0), ClO− 4 (0.5), HCO− 3 (0.5), gluconate− (0.3). In contrast to the OR conductance, glibenclamide was the most potent and DIDS the least potent blocker of L currents. An IC50 of 〉100 μm was observed for NPPB block. Neither OR of L chloride currents were affected by acutely or chronically increased intracellular cAMP and were not affected when intracellular Ca2+ levels were increased or decreased. The molecular identity and physiological role of OR and linear currents in mIMCD-3 cells are discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s002329900003
Permalink
