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Sustained CGRP1 receptor stimulation modulates development of EC coupling by cAMP/PKA signalling pathway in mouse skeletal myotubes
Author(s) -
Avila Guillermo,
Aguilar Citlalli I.,
RamosMondragón Roberto
Publication year - 2007
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2007.137687
Subject(s) - calcitonin gene related peptide , chemistry , medicine , long term potentiation , endocrinology , biophysics , stimulation , forskolin , receptor , biology , biochemistry , neuropeptide
We investigated modulation of excitation–contraction (EC) coupling by calcitonin gene‐related peptide (CGRP), which is released by motorneurons during neuromuscular transmission. Mouse skeletal myotubes were cultured either under control conditions or in the presence of 100 n m CGRP (∼4–72 h). T‐ and L‐type Ca 2+ currents, immobilization resistant charge movement, and intracellular Ca 2+ transients were characterized in whole‐cell patch‐clamp experiments. CGRP treatment increased the amplitude of voltage‐gated Ca 2+ release ((Δ F / F ) max ) ∼75–350% and moderately increased both maximal L ‐current conductance ( G max ) and charge movement ( Q max ). In contrast, CGRP treatment did not affect their corresponding voltage dependence of activation ( V 1/2 and k ) or T‐current density. CGRP treatment enhanced voltage‐gated Ca 2+ release in ∼4 h, whereas the effect on L ‐channel magnitude took longer to develop (∼24 h), suggesting that short‐term potentiation of EC coupling may lead to subsequent long‐term up‐regulation of DHPR expression. CGRP treatment also drastically increased caffeine‐induced Ca 2+ release in ∼4 h (∼400%). Thus, short‐term potentiation of EC coupling is due to an increase in sarcoplasmic reticulum Ca 2+ content. Both application of a phosphodiesterase inhibitor (papaverine) and a membrane‐permeant cAMP analogue (Db‐cAMP) produced a similar potentiation of EC coupling. Conversely, this potentiation was prevented by pretreatment with either CGRP1 receptor antagonist (CGRP 8‐37 ) or a PKA inhibitor (H‐89). Thus, CGRP acts through CGRP1 receptors and the cAMP/PKA signalling pathway to enhance voltage‐gated Ca 2+ release. Effects of CGRP on both EC coupling and L ‐channels were attenuated at later times during myotube differentiation. Therefore, we conclude that CGRP accelerates maturation of EC coupling.