Resting membrane potentials: a student test of alternate hypotheses

Area of Science:

• Physiology
• Cell Biology
• Neuroscience

Background:

• The frog sartorius muscle is a valuable model for teaching fundamental physiological concepts.
• Understanding membrane potential is crucial for comprehending cell function and excitability.

Purpose of the Study:

• To provide physiology students with a hands-on experiment demonstrating membrane phenomena and hypothesis testing.
• To teach students about membrane permeability, ionic gradients, and membrane voltage (Vm).

Main Methods:

• Frog sartorius myocytes were impaled with glass microelectrodes to measure Vm.
• Vm was recorded during alterations in extracellular potassium (K+) and the addition of a K+ channel blocker.
• Students applied the Nernst equilibrium and Goldman-Hodgkin-Katz equations to predict Vm.

Main Results:

• The experiment allowed direct observation of Vm changes in response to ionic environment modifications.
• Students determined which theoretical model (Nernst or Goldman-Hodgkin-Katz) better predicted the experimental Vm.
• Micromanipulation and microelectrode impalement techniques were successfully learned.

Conclusions:

• The frog sartorius muscle preparation effectively illustrates membrane voltage principles.
• Comparing theoretical models to experimental data enhances understanding of ionic influences on Vm.
• This experiment integrates practical skills with theoretical knowledge in membrane physiology.