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Problems and pitfalls in cable analysis in short tubular epithelia. Analysis of regional functional differences, a model
Author(s) -
Klein Georg,
Van Kerkhove Emmy
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a412
Subject(s) - midgut , leakage (economics) , leak , lumen (anatomy) , biophysics , anatomy , biology , chemistry , physics , microbiology and biotechnology , larva , botany , economics , macroeconomics , thermodynamics
Data from cable analysis give an estimate of the actual physiological values only, if there is no substantial electrical leak in the set‐up and if the R te is evenly distributed along the preparation. A model is proposed to assess the transepithelial resistance (R te ) of short tubular epithelia with unequally distributed R te . The midgut of the springtail Orchesella cincta (L.) is short and shows no obvious morphological differentiation. Nevertheless differences in transport function (e.g. R te ) along the length are to be expected. Midgut pieces of different lengths (0.2 to 1.4mm) were luminally perfused from the oral to the aboral end. The R te increased significantly from 70 Ω·cm 2 to 1268 Ω·cm 2 (p<0.00001; average: 380 ± 36SEM Ω·cm 2 ; n = 57). Estimates of R te from measurements in preparations with high R te , may be obscured by electrical leakage between the lumen and the surrounding bath. Extrapolating the input resistances of midgut pieces of different lengths to zero length gave an estimate of these seal resistances (372 kΩ). Midguts (0.25 to 1.5mm) were also perfused in the other direction, i.e. from aboral to oral end, to elucidate whether leakage or true differences in R te along the midgut explained the previous results. Overall the data confirmed a higher aboral R te . The R te distribution along the midgut could be mimicked by an electrical equivalent circuit. The midgut was divided into 10 subsequent loops in the model circuit. Inserting values for leakage, resistances and cell potentials, based on the experimental data, revealed, that the actual midgut R te μαψ ηαϖε ινχρεασεδ 45–ϕολδ ϕρομ 150 Ω·cm 2 at the oral side to 6700 Ω·cm 2 at the aboral side.