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Ion transport across the murine retinal pigment epithelium
Author(s) -
Arnason Sighvatur Saevar,
Skarphedinsdottir Sunna Björg,
Eysteinsson Thor
Publication year - 2013
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.27.1_supplement.1148.13
Subject(s) - transepithelial potential difference , retinal pigment epithelium , bumetanide , ion transporter , chemistry , ouabain , biophysics , purinergic receptor , retinal , retina , cotransporter , endocrinology , anatomy , extracellular , biology , biochemistry , sodium , membrane , organic chemistry , neuroscience
The retinal pigment epithelium (RPE) is important for the normal transport of ions and water from the subretinal space. Due to the small size of mice, ion transport across fresh murine RPE has not been studied in vitro. Sheets of RPE with the retina attached from normal mice were mounted in EasyMount Ussing chambers with an aperture of 0.031 cm 2 (Physiological Instruments Inc) with aireated 38°C Krebs. The short‐circuit current, I SC , and the transepithelial resistance, TER, was recorded with a voltage clamp apparatus. Initial I SC (n=7) was −17,6 ±4,5 μA/cm 2 , with apical side negative, and TER was 82,8 ±7,6 Ohm*cm 2 . The following substances were tested (30 min each, both apical and basolateral sides): ATP (100 μM) had no effect on the I SC . Epinephrine (100 μM) increased the I SC by 5%. Bumetanide (100 μM) inhibited the I SC from −16.1 ± 5.2 to −14.5 ± 5.4 μA/cm 2 . Ouabain (1 mM) induced a biphasic response, a rapid 6 min increase to −17.4 ± 2.6 μA/cm 2 , and a slower 30 min decrease to 36% of pre‐addition I SC . The Isc was reduced by low Cl − Krebs. Reducing the K + concentration on the apical side decreased the Isc, which was inhibited by 1 mM BaCl 2 . The mouse RPE preparation was stable for 2–3 hours. The results indicate that adrenergic but not purinergic receptors affect murine RPE ion transport as measured by the I SC . The ion transport is likely due to Cl − transport with some K + involvement, with the NaK‐ATPase serving as an important driving force.