Document Detail


Trifluoperazine-induced changes in swimming behavior of paramecium: evidence for two sites of drug action.
MedLine Citation:
PMID:  6478498     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Trifluoperazine (TFP), a drug that binds to Ca2+-calmodulin (CaM) complexes, altered swimming behavior not only in living paramecia, but also in reactivated, Triton-extracted "models" of the ciliate. By comparing the responses of living cells and models, we have ascertained that two sites of drug action exist in paramecium cilia. Swimming movements were recorded in darkfield stroboscopic flash photomicrographs; this permitted accurate quantitation of velocities and body-shape parameters. When living paramecia were incubated in a standard buffer containing 10 microM TFP, their speed of forward swimming fell over several minutes and their bodies shortened. Untreated paramecia backed up repeatedly and frequently upon transfer to a solution containing barium ions (the "barium dance"), but cells preincubated in TFP did not "dance." Instead they swam forward slowly for long periods of time without reversing and occasionally then exhibited abnormally prolonged reversals. W7 effects on swimming mimicked low doses of TFP, and the analog W5 did not visibly alter normal swimming patterns. These results suggest that TFP induces a decrease in the intracellular pCa of living paramecia, perhaps by reducing the efficiency of a calmodulin-activated calcium pump in the cell membrane. Paramecia extracted with Triton X-100 and reactivated to swim forward (7 greater than or equal to pCa greater than or equal to 6) were not affected by addition of up to 40 microM TFP to the reactivation medium. We conclude that the main drug effect in living cells is probably not at the axoneme. However, at low pCa, TFP directly affected the ciliary axoneme to shift its behavior to one characteristic of a higher pCa: TFP inhibited backward swimming in models reactivated at pCa less than 6; instead they swam forward or rocked in place. The mechanism of ciliary reversal in paramecium may therefore depend on an axonemal Ca2+-sensor, possibly bound CaM, which is affected by TFP only at low pCa, as has been postulated for other types of cilia.
Authors:
T Otter; B H Satir; P Satir
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Cell motility     Volume:  4     ISSN:  0271-6585     ISO Abbreviation:  Cell Motil.     Publication Date:  1984  
Date Detail:
Created Date:  1984-11-21     Completed Date:  1984-11-21     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  8207421     Medline TA:  Cell Motil     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  249-67     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Animals
Calcium / metabolism
Calmodulin / metabolism
Cilia / drug effects,  physiology
Movement
Paramecium / drug effects*,  physiology
Trifluoperazine / pharmacology*
Grant Support
ID/Acronym/Agency:
F32 GM 08986/GM/NIGMS NIH HHS; HL 22560/HL/NHLBI NIH HHS
Chemical
Reg. No./Substance:
0/Calmodulin; 117-89-5/Trifluoperazine; 7440-70-2/Calcium

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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