Kinetics of Cl-dependent K influx in human erythrocytes with and without external Na: effect of NEM
| Autor: | Deepak M. Kaji, Kahn T |
|---|---|
| Rok vydání: | 1985 |
| Předmět: |
Erythrocytes
Physiology Stereochemistry Potassium Sodium Kinetics chemistry.chemical_element Chlorides medicine Humans Nitrates Chemistry Biological Transport Cell Biology Membrane transport Culture Media Red blood cell medicine.anatomical_structure Ethylmaleimide Biophysics Human erythrocytes Cotransporter Intracellular |
| Zdroj: | American Journal of Physiology-Cell Physiology. 249:C490-C496 |
| ISSN: | 1522-1563 0363-6143 |
| Popis: | The majority of the ouabain-insensitive K influx in human erythrocytes is dependent on the presence of Cl. Recent studies have shown that a portion of the Cl-dependent K influx persists in the absence of external Na (Nao). It has been suggested that this Nao-independent component represents (K + Cl) cotransport, whereas the remainder of the Cl-dependent K influx seen on addition of external Na represents (Na + K + 2Cl) cotransport. In the present studies, the kinetics of Cl-dependent K influx were examined in the presence and absence of external Na, by varying external K and external Cl. Our studies suggest that the Nao-independent Cl-dependent pathway has a relatively low affinity for external K (Km 17-30 mM) in contrast to the high affinity of the Nao-augmented component (Km 3-4 mM). N-ethylmaleimide (NEM) stimulates the maximal velocity of the Nao-independent Cl-dependent K influx achievable without alteration of intracellular solutes but does not alter its Km for external K. In contrast, NEM has no stimulatory effect on the Nao-augmented component. The Cl dependence of the Nao-independent K influx is best described by a relatively flat curve with a mild upward concavity. The kinetic properties of the Nao-independent component of Cl-dependent K transport are very similar to those of the putative (K + Cl) cotransport pathway seen in low-K sheep erythrocytes.(ABSTRACT TRUNCATED AT 250 WORDS) |
| Databáze: | OpenAIRE |
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