PHYSIOLOGY OF EXCITABLE CELLS
Learning outcomes of the course unit
The aim of the course is to provide knowledge into the Hodgkin-Huxley theory of membrane excitability, usually only briefly underlined into General Physiology Courses. Here the theory is treated in detail with particular reference to some cell types, like prokaryotes, unicellular algae, plants, up to neurons and muscle cells.
Further aim of the course is to provide deep knowledge around the most used experimental techniques for measuring cellular excitability and its modulation.
Finally, the course aims to provide students with concepts needed to understand mechanisms of macroscopic cellular excitability, moving from the formal knowledge of their molecular mechanisms. For what concerns the cell physiology experimental techniques described during the course, students will only be required to apprehend what is functional in order to understand the investigated molecular and cellular mechanisms.
Students are expected to:
1) Know the molecular bases underlying cellular excitability
2) Distinguish, among the different electrophysiological approaches, those suitable to extract information at the molecular, cellular, and tissue level
3) Being able to study specific literature on cellular electrophysiology, resuming and presenting the content schematically
4) Being able to extract qualitative and quantitative information from electrophysiological cellular measurements, with reference to a limited number of papers discussed during the course
Basic concepts of Mathematics, Physics, Chemistry, Cellular Biology and Biochemistry are required. Solid knowledge of General Physiology is required.
Course contents summary
1. Mechanism of the membrane potential.
2. Mechanism of the action potential.
3. Techniques for measuring membrane potential (current clamp, voltage clamp, coupling clamp, action potential clamp, dynamic clamp).
4. Measuring gating processes of ion channels with voltage clamp technique.
5. Numerical reconstruction of the action potential from experimental data.
6. Action potential properties: rheobase, cronaxy, refractoriness,electrical restitution, dynamic restitution, input resistance.
7. Action potential propagation.
DEEPER INTO RECENT LITERATURE:
1. Cardiac pacemaker and its modulation
2. Experimental measurements of excitation-contraction coupling
3. Electrotonic modulation of the cardiac action potential repolarization
1. mechamism of membrane potential
2. mechanism of action potential
3. methods for the measure of membrane potential (current clamp, voltage clamp, coupling clamp, action potential clamp, dynamic clamp).
4. methods for measuring the gating properties of ion channels in voltage clamp.
5. numerical reconstruction of action potential from experimental data.
6. action potential properties: rheobase, cronaxy, refractoriness, electrical restitution, dynamic restitution, input resistance.
7. action potential propagation
Fisiologia e Biofisica delle cellule
V. Taglietti - C. Casella. EDISES
General concepts concerning the molecular mechanisms of cellular excitability will be discussed during oral lessons.
The introductory part of the course will present in greater detail concepts of membrane excitability already treated in previous courses of General Physiology.
The Hodgkin-Huxley theory of membrane excitability will be discussed in detail, together with its computational formulation, and with examples within neurons and cardiac cells.
Different excitable mechanisms will be explained within: prokaryotes, unicellular algae, protists, plants, neuronal and muscle cells.
Within the second part of the course, a number of recent scientific papers will be discussed concerning membrane excitability, its mechanism and modulation. The discussion of each article will be preceded by the presentation of the related general concepts. The working hypothesis of the authors, the description of the methods, and the study and discussion of the results will then be discussed as well. Some experimental techniques for measuring membrane excitability will be treated with particular detail, given their relevance for the understanding of the very concept of excitability.
The patch clamp technique, in its different configurations and in its more recent versions (coupling clamp, dynamic clamp), will be discussed with particular detail.
At least one seminar will be given by an external expert for the students within the course, and concerning particular aspects of cellular excitability treated within the oral lessons.
The slides projected during each lesson will be uploaded regularly on the digital platform Elly and will be part of the supporting material of the course, together with the suggested textbook.
Assessment methods and criteria
FINAL ORAL EXAMINATION.
Students will be allowed to prepare, for their final oral examination, the general concepts concerning the molecular mechanisms of cellular excitability, particularly Hodgkin-Huxley theory. This part is fully discussed in the reference book recommended for the course and in the additional material provided for the students on the website of the course, and discussed during oral lessons.
Students can otherwise choose to prepare, for the final examination, one of the scientific articles presented during the course. They will be required to present and discuss the hypothesis underlying the study, the experimental methods employed by the authors in order to test those hypothesis, and the obtained results. They will be required to discuss the article results and the related physiology concepts.