Effect of CCh pulses with rest time of R = 5 min on [Ca²⁺]_i oscillations.

(A) The individual [Ca2+]i from all 4 islets are shown in gray and their average is shown in black. The timing of the CCh pulses is shown by the “x”. The inset shows the natural period of these 4 islets ranged from 3.4–6.8 min (open circle), but all converged to 5 min during pulsing (filled circle) indicating 1:1 entrainment. (B) The synchronized response of the group is evident by the emergence of a pronounced band at an oscillation period of 5 min during the 55 min time that CCh was applied. See S8 and S9 Figs for results from the remaining R = 5 min groups. (C) The oscillation periods of all 12 islets tested with the R = 5 min pulse profile before (open circles) and during CCh pulsing (filled circles) are summarized.