scholarly journals An increase in cytosolic Ca2+ delays cAMP oscillations in Dictyostelium cells

1996 ◽  
Vol 319 (1) ◽  
pp. 323-327 ◽  
Author(s):  
Dieter MALCHOW ◽  
Ralph SCHALOSKE ◽  
Christina SCHLATTERER
Keyword(s):  
Light Scattering ◽  
Dictyostelium Discoideum ◽  
Response Curve ◽  
Phase Response Curve ◽  
Phase Delay ◽  
Phase Response ◽  
Transient Increase ◽  
Camp Synthesis ◽  
Similar Phase ◽  
Oscillatory Cycle

We have shown that calmidazolium (R24571) causes a transient increase in the cytosolic free Ca2+ concentration ([Ca2+]i) in Dictyostelium discoideum [Schlatterer and Schaloske (1996) Biochem. J. 313, 661–667]. Here we have used R24571 to artificially increase [Ca2+]i during light-scattering oscillations and have found that, depending on the time of addition during the oscillatory cycle, R24571 suppressed cAMP synthesis and delayed the next spike for several minutes. Addition of Ca2+ to the medium, which also elevates [Ca2+]i, induced phase delays and resulted in a similar phase response curve as R24571. The magnitude of the phase delay was correlated with the point during the oscillatory cycle at which Ca2+ was added, indicating that an artificial increase in [Ca2+]i also resets the phase of the intrinsic oscillator.

PH oscillations in cell suspensions of Dictyostelium discoideum: their relation to cyclic-amp signals

1978 ◽  
Vol 30 (1) ◽  
pp. 319-330
Author(s):  
D. Malchow ◽  
V. Nanjundiah ◽  
G. Gerisch
Keyword(s):  
Phase Shift ◽  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Response Curve ◽  
Phase Response Curve ◽  
Cell Suspensions ◽  
Phase Response ◽  
Temporary Increase ◽  
Rhythmic Stimulation

Cells of Dictyostelium discoideum known to release cyclic AMP (cAMP) rhythmically in the form of pulses, change with the same period of about 8 min the pH of their medium. The pH is used here as an indicator to investigate the effect of externally added cAMP pulses on the oscillations. Both a temporary increase in amplitude and a permanent phase shift can be induced. The phase-response curve indicates that the period can be increased and decreased by rhythmic stimulation with cAMP pulses.

Synchronization of two coupled pacemaker cells based on the phase response curve

2009 ◽  
Vol 4 (1) ◽  
pp. 57-66
Author(s):  
Hossein Gholizade-Narm ◽  
Asad Azemi ◽  
Morteza Khademi ◽  
Masoud Karimi-Ghartemani
Keyword(s):  
Response Curve ◽  
Phase Response Curve ◽  
Phase Response ◽  
Pacemaker Cells

Light effects on circadian timing system of a diurnal primate, the squirrel monkey

1985 ◽  
Vol 249 (2) ◽  
pp. R274-R280 ◽  
Author(s):  
T. M. Hoban ◽  
F. M. Sulzman
Keyword(s):  
Squirrel Monkey ◽  
Response Curve ◽  
Phase Response Curve ◽  
Phase Response ◽  
Day Length ◽  
Circadian Timing ◽  
Subjective Night ◽  
Timing System ◽  
Circadian Timing System ◽  
Light Effects

We examined light effects on the circadian timing system of the squirrel monkey. A phase-response curve to 1-h pulses of light was constructed for the drinking rhythm of six animals. The phase-response curve was the same type as that exhibited by nocturnal rodents, with phase delays occurring early in the subjective night and phase advances late in the subjective night. The range of entrainment of 10 monkeys to days with 1 h light and x h dark was determined. Five monkeys used to generate the phase-response curve were also used in the range of entrainment determination. For short light-dark cycles the range of entrainment was smaller than that expected, with no monkey entraining to a day length of less than 23.5 h.

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