Investigate the basic principles of intracellular recordings.

The aim of this experiment is to explore the physiology of several excitable cell types. Using a glass microelectrode to record from a muscle fiber, neuron, or alga cell, students will investigate the basic principles of intracellular recordings. These enclosed documents complement the Crawdad Lab Manual found at http://www.sinauer.com/detail.php?id=9474 .

Ionic Basis of Resting Potential This lab introduces intracellular recording of the crayfish abdominal superficial flexor muscle. Students change sodium and potassium ion concentrations in the extracellular fluid to show dependence of resting potential on potassium ions.

Snail Brain Neurons The brain of the snail has many large cells with interesting properties. Students usually see sodium and calcium action potentials, spontaneous firing, and rhythmic bursting. Students can investigate neural excitability by injecting current.

Ionic Basis of Action Potentials In this exercise, students examine the ionic basis of snail action potentials by altering ion concentrations and by pharmacological manipulation.

Plant Action Potential The freshwater alga Chara corallina fires action potentials when electrically stimulated. This illustrates the wide taxonomic distribution of voltage-gated channels and excitability. The action potentials are very long-lasting and clearly illustrate absolute and relative refractory periods. The Alga Chamber caters for the large Chara cells, making it easy to record action potentials from and watch features such as cytoplasmic streaming.