Cholinergic modulation of L-type calcium current in isolated sensory hair cells of the statocyst of octopus, Eledone cirrhosa.
Whole-cell voltage-clamp recordings from dissociated hair cells of the statocyst of octopus, Eledone cirrhosa, demonstrated that application of ACh, carbachol or muscarine (10 microM) reversibly decreased the amplitude of L-type calcium current (I(Ca,L)), while nicotine (10-100 microM) did not have any effect. Furthermore, atropine blocked the effect of ACh and agonists suggesting that ACh reduces I(Ca,L) through activation of muscarinic receptors. Internal dialysis of these cells with guanosine 5'-O-3-thiotriphosphate (GTPgammaS), a non-hydrolysable GTP analogue, mimicked the ACh-induced inhibition of I(Ca,L) and occluded any further ACh-induced inhibition. Internal dialysis of these hair cells with guanosine 5'-O-(2-thiodiphosphate) (GDPbetaS) reduced the ACh-induced inhibition I(Ca,L). The inhibitory effects of ACh were abolished by pre-incubation of these cells with pretussis toxin (PTX) suggesting that ACh-induced inhibition of I(Ca,L) involves a PTX-sensitive G protein pathway.
Chrachri
Abdesslam
A
University of Plymouth, School of Biological Sciences, Drake Circus, Plymouth PL4 8AA, UK. aacc@mba.ac.uk
Williamson
Roddy
R
D000818:Animals; D020746:Calcium Channels, L-Type / Q000502:physiology*; D018678:Cholinergic Agents / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006198:Hair Cells, Auditory / Q000187:drug effects* / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology; D049831:Octopodiformes / Q000187:drug effects* / Q000502:physiology*
D020746:Calcium Channels, L-Type; D018678:Cholinergic Agents