I. CONDUCTION: is reserved for the passage of an impulse along a axon or muscle fiber. Axonal conduction: stems largely from the work of Hodgkin and Husley: Energy-dependent active transport mechanism, Na+K+-ATPase. Transmembrane ionic currents produce local circuit currents around axons.
1. Tetradotoxins, puffer fish, selectively block axonal conduction; they do so by blocking the voltage-sensitive Na+ channel and preventing the increase in Na+ permeability associated with the rising phase of action potential.
2. Batrachotoxin, south American frog, an extremely potent steroidal alkaloid, produces paralysis through a selective increase in permeability of the Na+ channel, which induces a persistent depolarization.
3. Scorpion toxins are peptides that also cause persistent depolarization, but they do so by inhibiting the inactivation process.
II. TRANSMISSION:
1. Storage and release of transmitter.
2. Combination of the transmitter with post-junctional receptors and production of post-junctional potential.
3. Initiation of post-junctional activity.
4. Destruction or dissipation of the transmitter.
5. Non-electrogenic functions.
Nguồn: Goodman 11th edition, section III, chapter 6. p.137-180.