Contribution of l- and non-l-type calcium channels to voltage-gated calcium current and glucose-dependent insulin secretion in hit-t15 cells

L. S. Satin, Steven Tavalin, T. A. Kinard, J. Teague

Research output: Contribution to journalArticle

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Abstract

The pharmacological properties of voltage-gated Ca current and glucose-dependent insulin secretion were determined using the HIT insulinoma line to understand the role of Ca channels in stimulus-secretion coupling. The L-type Ca channel antagonist nimodipine inhibited a maximum of 50-55% of the peak Ca current, suggesting that L- and non-L-type channels contribute to Ca current. The L-agonist BAY K 8644 increased Ca current by 155%, whereas the N-channel blocker ω-conotoxin MVIIA reversibly blocked 35% of the peak Ca current. Total block with nimodipine and MVIIA was additive. Conotoxin MVIIC did not affect HIT Ca current. Prolonged depolarizations elicited rapidly and slowly inactivating Ca currents. Nimodipine partially inhibited transient current, but fully inhibited slowly inactivating current, suggesting that the former is mediated by L- and N-channels, and the latter is mediated by L-channels. Like slowly inactivating Ca current, glucose-dependent insulin secretion was fully inhibited by nimodipine and insensitive to MVIIA. BAY K potentiated secretion and antagonized nimodipine block. These results suggest that persistent Ca current is mediated by L-channels and is strongly coupled to insulin secretion, whereas transient Ca current is mediated by L- and N-channels and is weakly coupled. Sustained Ca influx may be preferentially coupled because glucose persistently depolarizes HIT cells and inactivates more transient Ca channel pathways.

Original languageEnglish (US)
Pages (from-to)4589-4601
Number of pages13
JournalEndocrinology
Volume136
Issue number10
DOIs
StatePublished - Jan 1 1995
Externally publishedYes

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Nimodipine
Calcium Channels
Insulin
Calcium
Glucose
Conotoxins
Insulinoma
Pharmacology

All Science Journal Classification (ASJC) codes

  • Endocrinology

Cite this

Contribution of l- and non-l-type calcium channels to voltage-gated calcium current and glucose-dependent insulin secretion in hit-t15 cells. / Satin, L. S.; Tavalin, Steven; Kinard, T. A.; Teague, J.

In: Endocrinology, Vol. 136, No. 10, 01.01.1995, p. 4589-4601.

Research output: Contribution to journalArticle

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