The resting membrane potential of Drosophila melanogaster larval muscle depends strongly on external calcium concentration

Meade

et al. 2021

Biology

The endotoxin lipopolysaccharide (LPS) from Gram-negative bacteria exerts a direct and rapid effect on tissues. While most attention is given to the downstream actions of the immune system in response to LPS, this study focuses on the direct actions of LPS on skeletal muscle in Drosophila melanogaster. It was noted in earlier studies that the membrane potential rapidly hyperpolarizes in a dose-dependent manner with exposure to LPS from Pseudomonas aeruginosa and Serratia marcescens. The response is transitory while exposed to LPS, and the effect does not appear to be due to calcium-activated potassium channels, activated nitric oxide synthase (NOS), or the opening of Cl− channels. The purpose of this study was to further investigate the mechanism of the hyperpolarization of the larval Drosophila muscle due to exposure of LPS using several different experimental paradigms. It appears this response is unlikely related to activation of the Na-K pump or Ca2+ influx. The unknown activation of a K+ efflux could be responsible. This will be an important factor to consider in treatments of bacterial septicemia and cellular energy demands.

Section: Discussionsupporting

confidence: 88%

Rapid and Direct Action of Lipopolysaccharide (LPS) on Skeletal Muscle of Larval Drosophila

Meade

et al. 2021

Biology

Journal of Neurogenetics

“…Additionally, the relationship between synaptic failure and resting membrane potential has been previously studied. A group found that RMP in Drosophila larval body wall muscles is directly correlated with EJP amplitude in electrophysiological recordings utilizing HL3 saline; consistent with our findings, they demonstrated that hyperpolarized RMPs were correlated with higher EJP amplitudes, whereas depolarized RMPs were correlated with lower EJP amplitudes (Krans, Parfitt, Gawera, Rivlin, & Hoy, 2010). Thus, synaptic transmission failure could be partly attributed to changes in RMP.…”

Section: Potential Downstream Targets Of the Pkg Pathwaysupporting

confidence: 90%

BK channels and a cGMP-dependent protein kinase (PKG) function through independent mechanisms to regulate the tolerance of synaptic transmission to acute oxidative stress at theDrosophilalarval neuromuscular junction

Bollinger

Sial

2018

“…HA causes muscle relaxation in houseflies [ 5 , 16 ], so we chose the Drosophila NMJ [ 19 , 20 ] to examine the effect of HA on synaptic transmission using intracellular recording. Before HA treatment in HL3 solution (containing 1.5 mM Ca 2+ ), the peak amplitude of evoked EJPs was 34.32 ± 5.03 mV.…”

Section: Resultsmentioning

confidence: 99%

Insight into the Mode of Action of Haedoxan A from Phryma leptostachya

Xinmin

et al. 2016

Toxins

Haedoxan A (HA) is a major active ingredient in the herbaceous perennial plant lopseed (Phryma leptostachya L.), which is used as a natural insecticide against insect pests in East Asia. Here, we report that HA delayed the decay rate of evoked excitatory junctional potentials (EJPs) and increased the frequency of miniature EJPs (mEJPs) on the Drosophila neuromuscular junction. HA also caused a significant hyperpolarizing shift of the voltage dependence of fast inactivation of insect sodium channels expressed in Xenopus oocytes. Our results suggest that HA acts on both axonal conduction and synaptic transmission, which can serve as a basis for elucidating the mode of action of HA for further designing and developing new effective insecticides.