Dependence of spontaneous electrical activity and basal prolactin release on nonselective cation channels in pituitary lactotrophs

Title:

Dependence of spontaneous electrical activity and basal prolactin release on nonselective cation channels in pituitary lactotrophs

Creator:

Marek Kučka, Karla Kretschmannová, Stanko S. Stojilković, Hana Zemková, and Tomić, M.

Identifier:

https://cdk.lib.cas.cz/client/handle/uuid:c559c31c-22d3-4527-be48-b7e86b13aaab
uuid:c559c31c-22d3-4527-be48-b7e86b13aaab

Subject:

Fyziologie člověka a srovnávací fyziologie, fyziologie člověka, human physiology, TRPC channels, GH3 cells, calcium influx, action potentials, resting membrane potential, 14, and 612

Type:

article, články, model:article, and TEXT

Description:

All secretory anterior pituitary cells fire action potentials spontaneously and exhibit a high resting cation conductance, but the channels involved in the background permeability have not been identified. In cultured lactotrophs and immortalized GH3 cells, replacement of extracellular Na+ with large organic cations, but not blockade of voltage-gated Na+ influx, led to an instantaneous hyperpolarization of cell membranes that was associated with a cessation of spontaneous firing. When cells were clamped at –50 mV, which was close to the resting membrane potential in these cells, replacement of bath Na+ with organic cations resulted in an outward-like current, reflecting an inhibition of the inward holding membrane current and indicating loss of a background-depolarizing conductance. Quantitative RTPCR analysis revealed the high expression of mRNA transcripts for TRPC1 and much lower expression of TRPC6 in both lactotrophs and GH3 cells. Very low expression of TRPC3, TRPC4, and TRPC5 mRNA transcripts were also present in pituitary but not GH3 cells. 2-APB and SKF-96365, relatively selective blockers of TRPC channels, inhibited electrical activity, Ca2+ influx and prolactin release in a concentration-dependent manner. Gd3+, a common Ca2+ channel blocker, and flufenamic acid, an inhibitor of non-selective cation channels, also inhibited electrical activity, Ca2+ influx and prolactin release. These results indicate that nonselective cation channels, presumably belonging to the TRPC family, contribute to the background depolarizing conductance and firing of action potentials with consequent contribution to Ca2+ influx and hormone release in lactotrophs and GH3 cells., M. Kučka ... [et al.]., and Obsahuje seznam literatury

Language:

English

Rights:

http://creativecommons.org/licenses/by-nc-sa/4.0/
policy:public

Source:

Physiological research | 2012 Volume:61 | Number:3

Harvested from:

CDK

Metadata only:

false