Role of calcium influx through voltage-operated calcium channels and of calcium mobilization in the physiology of Schistosoma mansoni muscle contractions

D.L. Mendonca-Silva, E. Novozhilova, P.J.R. Corbett, C.L.M. Silva, F. Noel, Mark Totten, Aaron Maule, T.A. Day

Research output: Contribution to journalArticle

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Abstract

We tested the hypothesis that voltage-operated Ca2+ channels mediate an extracellular Ca2+ influx in muscle fibres from the human parasite Schistosoma mansoni and, along with Ca2+ mobilization from the sarcoplasmic reticulum, contribute to Muscle contraction. Indeed, whole-cell voltage clamp revealed voltage-gated inward currents carried by divalent ions with a peak current elicited by steps to + 20 mV (from a holding potential of -70 mV). Depolarization of the fibres by elevated extracellular K+ elicited contractions that were completely dependent on extracellular Ca2+ and inhibited by nicardipine (half inhibition at 4(.)1 mu M). However these contractions were not very sensitive to other classical blockers of voltage-gated Ca2+ channels, indicating that the schistosome Muscle channels have an atypical pharmacology when compared to their mammalian counterparts. Furthermore, the contraction induced by 5 mM caffeine was inhibited after depletion of the sarcoplasmic reticulum either with thapsigargin (10 mu M) or ryanodine (10 mu M). These data suggest that voltage-operated Ca2+ channels docontribute to S. mansoni contraction as does the mobilization of stored Ca2+, despite the small volume of sarcoplasmic reticulum in schistosome smooth muscles.
Original languageEnglish
Pages (from-to)67-74
Number of pages8
JournalParasitology
Volume133
Issue number1
DOIs
Publication statusPublished - Jul 2006

ASJC Scopus subject areas

  • Immunology
  • Parasitology

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