FMRFamide-Like Peptides (FLPs) Enhance Voltage-Gated Calcium Currents to Elicit Muscle Contraction in the Human Parasite Schistosoma mansoni

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Novozhilova, Ekaterina
Qian, Hai
McVeigh, Paul
Robertson, Alan
Zamanian, Mostafa
Maule, Aaron
Day, Timothy
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Kimber, Michael
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Biomedical Sciences

The Department of Biomedical Sciences aims to provide knowledge of anatomy and physiology in order to understand the mechanisms and treatment of animal diseases. Additionally, it seeks to teach the understanding of drug-action for rational drug-therapy, as well as toxicology, pharmacodynamics, and clinical drug administration.

The Department of Biomedical Sciences was formed in 1999 as a merger of the Department of Veterinary Anatomy and the Department of Veterinary Physiology and Pharmacology.

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  • College of Veterinary Medicine (parent college)
  • Department of Veterinary Anatomy (predecessor, 1997)
  • Department of Veterinary Physiology and Pharmacology (predecessor, 1997)

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Schistosomes are amongst the most important and neglected pathogens in the world, and schistosomiasis control relies almost exclusively on a single drug. The neuromuscular system of schistosomes is fertile ground for therapeutic intervention, yet the details of physiological events involved in neuromuscular function remain largely unknown. Short amidated neuropeptides, FMRFamide-like peptides (FLPs), are distributed abundantly throughout the nervous system of every flatworm examined and they produce potent myoexcitation. Our goal here was to determine the mechanism by which FLPs elicit contractions of schistosome muscle fibers. Contraction studies showed that the FLP Tyr-Ile-Arg-Phe-amide (YIRFamide) contracts the muscle fibers through a mechanism that requires Ca2+ influx through sarcolemmal voltage operated Ca2+ channels (VOCCs), as the contractions are inhibited by classical VOCC blockers nicardipine, verapamil and methoxyverapamil. Whole-cell patch-clamp experiments revealed that inward currents through VOCCs are significantly and reversibly enhanced by the application of 1 µM YIRFamide; the sustained inward currents were increased to 190% of controls and the peak currents were increased to 180%. In order to examine the biochemical link between the FLP receptor and the VOCCs, PKC inhibitors calphostin C, RO 31–8220 and chelerythrine were tested and all produced concentration dependent block of the contractions elicited by 1 µM YIRFamide. Taken together, the data show that FLPs elicit contractions by enhancing Ca2+ influx through VOCC currents using a PKC-dependent pathway.


This article is from PLoS Negl Trop Dis 4(8): e790. doi:10.1371/journal.pntd.0000790. Posted with premission.

Fri Jan 01 00:00:00 UTC 2010