Calcium channel subtypes and exocytosis in chromaffin cells: a different view from the intact rat adrenal
| Autor: | R. Jaén, Antonio G. García, Francisco Santana, Pedro Michelena, Ricardo Borges |
|---|---|
| Rok vydání: | 1999 |
| Předmět: |
medicine.medical_specialty
Calcium Channels L-Type Chromaffin Cells Stimulation In Vitro Techniques Biology complex mixtures Splanchnic nerves Exocytosis Rats Sprague-Dawley Calcium Channels N-Type Catecholamines Internal medicine medicine Animals Pharmacology Voltage-dependent calcium channel Calcium channel Depolarization General Medicine Calcium Channel Blockers Acetylcholine Electric Stimulation Rats Endocrinology medicine.anatomical_structure Adrenal Medulla Potassium Catecholamine Female Calcium Channels medicine.drug |
| Zdroj: | Naunyn-Schmiedeberg's Archives of Pharmacology. 360:33-37 |
| ISSN: | 1432-1912 0028-1298 |
| Popis: | In the intact rat adrenal gland perfused with an oxygenated Krebs-bicarbonate solution at 37 degrees C, the electrical field stimulation of splanchnic nerves (100 V, 0.5 ms duration, 10 Hz during 10 s) produced transient catecholamine release peaks that were reproduced in subsequent stimuli, applied at 8-min intervals. Omega-Conotoxin GVIA (0.3 microM) caused only a modest inhibition of the secretory response, suggesting that the N-subtype of voltage-dependent Ca2+ channels are scarcely involved in such a response. Both omega-conotoxin MVIIC (1 microM) and furnidipine (1 microM) halved the secretion, suggesting that the L- and P/Q-types of Ca2+ channels were involved. N-type Ca2+ channels appear to be involved in the maintenance of secretion in response to sustained stimulus since omega-conotoxin GVIA (0.3 microM) reduced the catecholamine output to 28%. When secretion was elicited by acetylcholine (10 microM), furnidipine reduced the catecholamine release by 50% and omega-conotoxin MVIIC by 40%, whereas omega-conotoxin GVIA did not modify the response. The K+-induced secretory responses (23.6 mM K+, 15 s) were reduced 75% by furnidipine and 45% by omega-conotoxin MVIIC, indicating that this type of stimulation preferentially recruited L-type channels. These data show that electrical stimulation recruits Ca2+ channel subtypes different from those recruited by direct depolarization of chromaffin cells. |
| Databáze: | OpenAIRE |
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