Analysis of various physiological salines for heart rate, CNS function, and synaptic transmission at neuromuscular junctions in Drosophila melanogaster larvae

J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2014 Jan;200(1):83-92. doi: 10.1007/s00359-013-0864-0. Epub 2013 Nov 5.


Drosophila serves as a playground for examining the effects of genetic mutations on development, physiological function and behavior. Many physiological measures that address the effects of mutations require semi-intact or cultured preparations. To obtain consistent physiological recordings, cellular function needs to remain viable. Numerous physiological salines have been developed for fly preparations, with emphasis on nervous system viability. The commonly used saline drifts in pH and will cause an alteration in the heart rate. We identify a saline that maintains a stable pH and physiological function in the larval heart, skeletal neuromuscular junction, and ventral nerve cord preparations. Using these common assays, we screened various pH buffers of differing concentrations to identify optimum conditions. Buffers at 25 mM produce a stable heart rate with minimal variation in pH. Excitatory junction potentials evoked directly on larval muscles or through sensory-CNS-motor circuits were unaffected by at buffers at 25 mM. The salines examined did not impede the modulatory effect of serotonin on heart rate or neural activity. Together, our results indicate that the higher buffer concentrations needed to stabilize pH in HL3 hemolymph-like saline do not interfere with the acute function of neurons or cardiac myocytes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Buffers
  • Central Nervous System / drug effects
  • Central Nervous System / physiology
  • Drosophila melanogaster / drug effects
  • Drosophila melanogaster / physiology*
  • Evoked Potentials / drug effects
  • Heart / drug effects
  • Heart / physiology
  • Heart Rate / drug effects
  • Hemolymph
  • Hydrogen-Ion Concentration
  • Larva / drug effects
  • Larva / physiology
  • Muscles / drug effects
  • Muscles / physiology
  • Neuromuscular Junction / drug effects*
  • Neuromuscular Junction / physiology
  • Sensory Receptor Cells / drug effects
  • Sensory Receptor Cells / physiology
  • Serotonin / metabolism
  • Sodium Chloride / chemistry
  • Sodium Chloride / pharmacology*
  • Synaptic Transmission / drug effects*
  • Synaptic Transmission / physiology


  • Buffers
  • Serotonin
  • Sodium Chloride