title: A videomicroscopic study of the effect of l-cis-diltiazem on the photobehavior of Stentor coeruleus.
abstract: The protozoan ciliate Stentor coeruleus displays a step-up photophobic response to an increase in light intensity in its environment. The motile response consists of a delayed stop of ciliary beating and transient ciliary reversal period. Such light-avoiding behavior was significantly influenced by an incubation of cells with l-cis-diltiazem, a common blocker of cyclic guanosine monophosphate (cGMP)-gated ion channel conductance. The introduction of l-cis-diltiazem to the medium induced ciliary reversal in control cells, mimicking the step-up photophobic response. In light-stimulated ciliates, the presence of this inhibitor caused a substantial decrease of the latency of ciliary stop response, prolongation of the ciliary reversal duration and also an increase of cell photoresponsiveness in a dose- and time-dependent manner. The obtained behavioral results support the suggestion that the photosensitive ciliate S. coeruleus possesses cGMP-gated channels, which may be involved in the process of light signal transduction for the motile photophobic response.
authors.affiliation: Department of Cell Biology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland.
authors.forename: Miroslawa
authors.initials: M
authors.lastname: Walerczyk
authors.forename: Hanna
authors.initials: H
authors.lastname: Fabczak
authors.forename: Stanislaw
authors.initials: S
authors.lastname: Fabczak
mesh_terms: D000818:Animals; D016798:Ciliophora / Q000187:drug effects* / Q000502:physiology / Q000528:radiation effects; D004110:Diltiazem / Q000494:pharmacology*; D007473:Ion Channels / Q000037:antagonists & inhibitors; D018715:Microscopy, Video; D009068:Movement; D018462:Photobiology
chemical_list: D007473:Ion Channels; D004110:Diltiazem