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Fig. 8. Action potentials recorded in 46 d.p.f. zebrafish inner muscle.
(A,B) Although no amount of depolarization of the inner muscle was found to
elicit more than one spike, further spiking could be elicited in response to a
second depolarization following a brief (>25 ms) return to the `resting'
potential in (A) Normal solution and (B) low Cl solution.
(C,D) The minimal interstimulus interval required to elicit a second spike was
greatly diminished by hyperpolarizing the membrane between stimuli. The
recovery of the action potential was graded rather than all-or-none. (C)
Normal solution, (D) in low Cl solution.