title: Calcium channel blockers inhibit galvanotaxis in human keratinocytes.
abstract: Directed migration of keratinocytes is essential for wound healing. The migration of human keratinocytes in vitro is strongly influenced by the presence of a physiological electric field and these cells migrate towards the negative pole of such a field (galvanotaxis). We have previously shown that the depletion of extracellular calcium blocks the directional migration of cultured human keratinocytes in an electric field (Fang et al., 1998; J Invest Dermatol 111:751-756). Here we further investigate the role of calcium influx on the directionality and migration speed of keratinocytes during electric field exposure with the use of Ca(2+) channel blockers. A constant, physiological electric field strength of 100 mV/mm was imposed on the cultured cells for 1 h. To determine the role of calcium influx during galvanotaxis we tested the effects of the voltage-dependent cation channel blockers, verapamil and amiloride, as well as the inorganic Ca(2+) channel blockers, Ni(2+) and Gd(3+) and the Ca(2+) substitute, Sr(2+), on the speed and directionality of keratinocyte migration during galvanotaxis. Neither amiloride (10 microM) nor verapamil (10 microM) had any effect on the galvanotaxis response. Therefore, calcium influx through amiloride-sensitive channels is not required for galvanotaxis, and membrane depolarization via K(+) channel activity is also not required. In contrast, Sr(2+) (5 mM), Ni(2+) (1-5 mM), and Gd(3+) (100 microM) all significantly inhibit the directional migratory response to some degree. While Sr(2+) strongly inhibits directed migration, the cells exhibit nearly normal migration speeds. These findings suggest that calcium influx through Ca(2+) channels is required for directed migration of keratinocytes during galvanotaxis and that directional migration and migration speed are probably controlled by separate mechanisms.
authors.affiliation: Section of Molecular and Cellular Biology, University of California, Davis 95616, USA.
authors.forename: Donna R
authors.initials: DR
authors.lastname: Trollinger
authors.forename: R Rivkah
authors.initials: RR
authors.lastname: Isseroff
authors.forename: Richard
authors.initials: R
authors.lastname: Nuccitelli
mesh_terms: D000584:Amiloride / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002465:Cell Movement / Q000502:physiology*; D002478:Cells, Cultured; D004558:Electric Stimulation / Q000379:methods; D005682:Gadolinium / Q000494:pharmacology; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D018715:Microscopy, Video; D009532:Nickel / Q000494:pharmacology; D055672:Static Electricity; D013324:Strontium / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology
chemical_list: D002121:Calcium Channel Blockers; D000584:Amiloride; D009532:Nickel; D005682:Gadolinium; D014700:Verapamil; D002118:Calcium; D013324:Strontium