Learning objectives
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. Further aim of the course is to provide deep knowledge concerning 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 be required to apprehend what is functional in order to understand the investigated molecular and cellular mechanisms.
Prerequisites
Basic concepts of Mathematics, Physics, Chemistry, Cellular Biology and Biochemistry are required. Solid knowledge of General Physiology is required.
Course unit content
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
Full programme
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
Bibliography
Fisiologia e Biofisica delle cellule
V. Taglietti - C. Casella
Edises
Ed. 2015
The Physiology of Excitable Cells, 4th edition
David J. Aidley, Cambridge University Press
https://doi.org/10.1017/CBO9781139171182
LITERATURE:
1. Action potential duration, rate of stimulation, and intracellular sodium.
Carmeliet E.
J Cardiovasc Electrophysiol. 2006 May;17 Suppl 1:S2-S7. Review.
2. Electrotonic modulation of electrical activity in rabbit atrioventricular
node myocytes.
Spitzer KW, Sato N, Tanaka H, Firek L, Zaniboni M, Giles WR.
Am J Physiol. 1997 Aug;273(2 Pt 2):H767-76.
3. Conduction between isolated rabbit Purkinje and ventricular myocytes
coupled by a variable resistance.
Huelsing DJ, Spitzer KW, Cordeiro JM, Pollard AE.
Am J Physiol. 1998 Apr;274(4):H1163-73.
4. Beat-to-beat repolarization variability in ventricular myocytes and its
suppression by electrical coupling.
Zaniboni M, Pollard AE, Yang L, Spitzer KW.
Am J Physiol Heart Circ Physiol. 2000 Mar;278(3):H677-87.
5. Temporal variability of repolarization in rat ventricular myocytes paced
with time-varying frequencies.
Zaniboni M, Cacciani F, Salvarani N.
Exp Physiol. 2007 Sep;92(5):859-69.
6. Cardiac excitation-contraction coupling.
Bers DM.
Nature. 2002 Jan 10;415(6868):198-205. Review.
7. Cell-specific Dynamic Clamp analysis of the role of funny If current in
cardiac pacemaking. Ravagli E1, Bucchi A2, Bartolucci C1, Paina
M2, Baruscotti M2, DiFrancesco D2, Severi S3.
Prog Biophys Mol Biol. 2016 Jan;120(1-3):50-66.
Teaching methods
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.
Assessment methods and criteria
FINAL ORAL EXAMINATION.
The final oral examination will be divided into two parts. In the first, the comprehension of the molecular mechanisms of cellular excitability, particularly the Hodgkin-Huxley theory, the electrotonic modulation of excitability and the excitation-contraction coupling, will be verified. 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. In the second part students will be required to discuss one of the scientific articles presented during the course, the underlying hypothesis, the experimental methods and the obtained results.
Other information
Even though the following topics are not strictly required to pass the final examination, nevertheless they are highly recommended. Supporting material will be provided at the beginning of the course:
1. Introduction to ordinary differential equations
2. Introduction to numerical analysis
3. Introduction to Matlab
2030 agenda goals for sustainable development
3, 4, 15
