Fig. 3.

Markovian models of receptor channel activity. a Simplest Markovian model of a receptor channel, with two unitary states: open (O) and closed (C). The transition rates describing channel opening and closure are respectively k_o and k_c. Both transition rates are a function of the agonist concentration [A]. b Application of the two-states model to steady-state situations. K is the equilibrium constant, and depends on agonist concentration. c MWC model. L, r and K are constants depending on receptor structure and [G] is the GABA concentration. The open states are O (no GABA bound), OG (one GABA) and OG₂ (two GABA); likewise, C, CG and CG2 are the close states