ISSN:
1432-1912
Keywords:
Key words Adrenal medulla
;
Chromaffin cells
;
Splanchnic nerve
;
Calcium channels
;
Exocytosis
;
Catecholamine release
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract In the intact rat adrenal gland perfused with an oxygenated Krebs-bicarbonate solution at 37°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. ω-Conotoxin GVIA (0.3 µM) 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 ω-conotoxin MVIIC (1 µM) and furnidipine (1 µM) 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 ω-conotoxin GVIA (0.3 µM) reduced the catecholamine output to 28%. When secretion was elicited by acetylcholine (10 µM), furnidipine reduced the catecholamine release by 50% and ω-conotoxin MVIIC by 40%, whereas ω-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 ω-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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s002109900041
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