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Cl- currents activated by extracellular nucleotides in human bronchial cells
O Zegarra-Moran1, O Sacco, L Romano
1Laboratorio di Genetica Molecolare, Istituto Giannina Gastini, Genova, I-16148 Italy.
The Journal of Membrane Biology
|April 1, 1997
Summary
Extracellular nucleotides like ATP and UTP activate two distinct calcium-dependent chloride currents in human bronchial cells. These currents, a transient phase (Ip) and a sustained phase (Is), exhibit different properties and sensitivities.
Area of Science:
- Cellular Physiology
- Ion Channel Function
- Respiratory Medicine
Background:
- Extracellular nucleotides play roles in cellular signaling.
- Human bronchial cells possess complex responses to stimuli.
- Understanding ion channel activity is crucial for respiratory health.
Purpose of the Study:
- To investigate the mechanisms by which extracellular nucleotides activate ion currents in human bronchial cells.
- To differentiate the characteristics of transient and sustained currents induced by ATP and UTP.
- To elucidate the role of intracellular calcium and chloride ions in these responses.
Main Methods:
- Perforated-patch clamp technique on human bronchial cells.
- Stimulation with adenosine triphosphate (ATP) and uridine triphosphate (UTP).
- Pharmacological manipulation using BAPTA/AM, niflumic acid, and 1,9-dideoxyforskolin; ionic substitution with aspartate.
Main Results:
- ATP/UTP induced a large transient current (Ip) and a smaller sustained current (Is).
- Both Ip and Is were dependent on intracellular calcium (Ca2+).
- Ip was identified as a Ca2+-activated Cl- current, while Is was also Ca2+-dependent but distinct.
Conclusions:
- Extracellular nucleotides activate two distinct Ca2+-dependent chloride currents in human bronchial cells.
- The transient current (Ip) is highly selective for chloride ions, whereas the sustained current (Is) shows less selectivity.
- These findings contribute to understanding nucleotide signaling and ion transport in the airways.