The ς-ligand (+)-pentazocine depresses M current and enhances calcium conductances in frog melanotrophs
| Autor: | F. le Foll, Ludovic Galas, O. Soriani, Lionel Cazin, Hubert Vaudry, Francois Joseph Roman |
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| Rok vydání: | 1999 |
| Předmět: |
Male
Pentazocine medicine.medical_specialty Physiology Narcotic Antagonists Endocrinology Diabetes and Metabolism Ligands Rana Cytosol Pituitary Gland Posterior Physiology (medical) Internal medicine M current medicine Animals Receptors sigma Melanocyte-Stimulating Hormones Patch clamp Cells Cultured Rana ridibunda Voltage-dependent calcium channel Chemistry Electric Conductivity Stereoisomerism Electrophysiology Kinetics Melanotrophs Endocrinology Barium Potassium GRENOUILLE Calcium medicine.drug |
| Zdroj: | American Journal of Physiology-Endocrinology and Metabolism. 277:E73-E80 |
| ISSN: | 1522-1555 0193-1849 |
| Popis: | Gramicidin-perforated patch clamp experiments and microfluorimetric measurements were performed to study the ionic mechanisms involved in the ς-receptor-mediated stimulation of frog ( Rana ridibunda) pituitary melanotrophs. The ς-ligand (+)-pentazocine (50 μM) depressed a sustained outward K+current. The kinetic properties of this K+component, investigated by analyzing tail currents, were reminiscent of those of the M current ( IM), with an activation threshold close to −60 mV, a −21-mV half-maximal activation potential, and two-component exponential deactivation kinetics at −90 mV. (+)-Pentazocine (20 μM) produced a 12-mV rightward shift of the activation curve and accelerated the deactivation rate of the tail current. It is also demonstrated that (+)-pentazocine (20 μM) reversibly increased both voltage-dependent calcium conductances and internal calcium level. Altogether, these results suggest that the ς-receptor-induced modulation of IMand calcium currents likely underlies the increase of intracellular [Ca2+]. |
| Databáze: | OpenAIRE |
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