Abstract
Previous studies in cultured rat hepatocytes revealed that initial uptake of sulfobromophthalein (BSP) was markedly reduced upon removal of Cl- from the medium. In the present study, unidirectional Cl- gradients were established in short-term cultured rat hepatocytes and their effect on BSP uptake was determined. These investigations revealed that BSP uptake requires external CT- and is not stimulated by unidirectional Cl- gradients, suggesting that BSP transport is not coupled to Cl- transport. In contrast, BSP transport is stimulated by an inside-to-outside OH- gradient, consistent with OH- exchange or H+ cotransport. As the presence of Cl- is essential for but not directly coupled to BSP transport, binding of 35S-BSP to hepatocytes was determined at 4°C. This revealed an ∼ 10-fold higher affinity of cells for BSP in the presence as compared to the absence of Cl- (Ka = 3.2±0.8 vs. 0.42±0.09 μM-1; P < 0.02). Affinity of BSP for albumin was Cl--independent, and was ∼ 10% of its affinity for cells in the presence of Cl-. These results indicate that extracellular Cl- modulates the affinity of BSP for its hepatocyte transporter.
Original language | English (US) |
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Pages (from-to) | 1496-1502 |
Number of pages | 7 |
Journal | Journal of Clinical Investigation |
Volume | 87 |
Issue number | 5 |
DOIs | |
State | Published - May 1991 |
Keywords
- Albumin binding
- Chloride transport
- Cultured hepatocytes
- Sulfobromophthalein
- Transport
ASJC Scopus subject areas
- General Medicine