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A role for Q type Ca 2+ channels in neurotransmission in the rat urinary bladder
Author(s) -
Frew Robert,
Lundy Paul M.
Publication year - 1995
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1995.tb16378.x
Subject(s) - omega , neurotransmission , voltage dependent calcium channel , chemistry , medicine , physics , calcium , receptor , biochemistry , quantum mechanics
1 In isolated bladder strips of the rat, a substantial component (46%) of the Ca 2+ ‐dependent contractile response to electrical field stimulation (5 Hz) was resistant to combined block of both N and P type Ca 2+ channels by ω‐conotoxin‐GVIA (300 nM) and ω‐agatoxin‐IVA (100 nM) respectively. 2 The resistant portion (non‐N, non‐P) was sensitive to ω‐conotoxin‐MVIIC (3 μ M ), which in addition to N and P also blocks Q type channels at this concentration. ω‐Conotoxin‐MVIIC administered alone, inhibited the neurogenic response to the same degree as that observed in the combined presence of ω‐agatoxin‐IVA, ωconotoxin‐GVIA and ω‐conotoxin‐MVIIC. 3 ω‐Agatoxin‐IVA (100 nM), a concentration that fully inhibits P type channels, had a negligible effect on the neurogenic response. Following blockade of N type Ca 2+ channels with ω‐conotoxin‐GVIA (300 μ M ), ω‐agatoxin‐IVA (3 μ M ) (a concentration well above that used to block P channels, inhibits Q type channels, but spares N type channels), inhibited the residual response to the same degree as ω‐conotoxin‐MVIIC alone. 4 Results suggest that neurotransmission in rat urinary bladder is supported by both N and Q type Ca 2+ channels.