Effects of osmotic shrinkage on voltage-gated Ca2+ channel currents in rat anterior pituitary cells
| Autor: | Shlomo Ben-Tabou De-Leon, Galia Ben-Zeev, Itzhak Nussinovitch |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
Male
medicine.medical_specialty Pituitary gland Calcium Channels L-Type Physiology Hypertonic Solutions Biology Membrane Potentials Anterior pituitary Osmotic Pressure Pituitary Gland Anterior Internal medicine medicine Extracellular Electric Impedance Osmotic pressure Animals Secretion Voltage-gated ion channel Osmotic concentration Voltage-dependent calcium channel Rats Inbred Strains Cell Biology Water-Electrolyte Balance Rats Actin Cytoskeleton Endocrinology medicine.anatomical_structure Biophysics Isotonic Solutions Ion Channel Gating |
| Zdroj: | American journal of physiology. Cell physiology. 290(1) |
| ISSN: | 0363-6143 |
| Popis: | Increased extracellular osmolarity ([Os]e) suppresses stimulated hormone secretion from anterior pituitary cells. Ca2+ influx may mediate this effect. We show that increase in [Os]e (by 18–125%) differentially suppresses L-type and T-type Ca2+ channel currents ( IL and IT, respectively); IL was more sensitive than IT. Hyperosmotic suppression of IL depended on the magnitude of increase in [Os]e and was correlated with the percent decrease in pituitary cell volume, suggesting that pituitary cell shrinkage can modulate L-type currents. The hyperosmotic suppression of IL and IT persisted after incubation of pituitary cells either with the actin-disrupter cytochalasin D or with the actin stabilizer phalloidin, suggesting that the actin cytoskeleton is not involved in this modulation. The hyperosmotic suppression of Ca2+ influx was not correlated with changes in reversal potential, membrane capacitance, and access resistance. Together, these results suggest that the hyperosmotic suppression of Ca2+ influx involves Ca2+ channel proteins. We therefore recorded the activity of L-type Ca2+ channels from cell-attached patches while exposing the cell outside the patch pipette to hyperosmotic media. Increased [Os]e reduced the activity of Ca2+ channels but did not change single-channel conductance. This hyperosmotic suppression of Ca2+ currents may therefore contribute to the previously reported hyperosmotic suppression of hormone secretion. |
| Databáze: | OpenAIRE |
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