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.jpg): Failed to open stream: No such file or directory in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 117 J+Undergrad+Neurosci+Educ
2015 ; 14
(1
): A82-6
Nephropedia Template TP
gab.com Text
Twit Text FOAVip
Twit Text #
English Wikipedia
Excitable Membranes and Action Potentials in Paramecia: An Analysis of the
Electrophysiology of Ciliates
#MMPMID26557800
Schlaepfer CH
; Wessel R
J Undergrad Neurosci Educ
2015[Fal]; 14
(1
): A82-6
PMID26557800
show ga
The ciliate Paramecium caudatum possesses an excitable cell membrane whose action
potentials (APs) modulate the trajectory of the cell swimming through its
freshwater environment. While many stimuli affect the membrane potential and
trajectory, students can use current injection and extracellular ionic
concentration changes to explore how APs cause reversal of the cell's motion.
Students examine these stimuli through intracellular recordings, also gaining
insight into the practices of electrophysiology. Paramecium's large size of
around 150 µm, simple care, and relative ease to penetrate make them ideal model
organisms for undergraduate students' laboratory study. The direct link between
behavior and excitable membranes has thought provoking evolutionary implications
for the study of paramecia. Recording from the cell, students note a small
resting potential around -30 mV, differing from animal resting potentials. By
manipulating ion concentrations, APs of the relatively long length of 20-30 ms up
to several minutes with depolarizations maxing over 0 mV are observed. Through
comparative analysis of membrane potentials and the APs induced by either calcium
or barium, students can deduce the causative ions for the APs as well as the
mechanisms of paramecium APs. Current injection allows students to calculate
quantitative electric characteristics of the membrane. Analysis will follow the
literature's conclusion in a V-Gated Ca(++) influx and depolarization resulting
in feedback from intracellular Ca(++) that inactivates V-Gated Ca(++) channels
and activates Ca-Dependent K(+) channels through a secondary messenger cascade
that results in the K(+) efflux and repolarization.