Intracellular Ca²⁺ oscillations, initiated by the activation of IP₃ receptors and orchestrated via intricate positive and negative feedback loops, can be subject to frequency modulation, an example of which is the increase in oscillation frequency with increasing stimulus strength. Caffeine is known to bind to and sensitize the ryanodine receptors, resulting in their opening in response to lower calcium ion concentrations. Do you think caffeine would tend to increase (I) or decrease (D) the frequency of calcium ion oscillations in stimulated cells? Write down I or D as your answer.

Question

Quizplus · Accepted Answer

The effect of channel sensitization to Ca²⁺ is comparable to that of increased Ca²⁺ concentration, i.e. higher-frequency oscillations. The frequency as well as the amplitude of the Ca²⁺ spikes can also be modulated by other mechanisms.

Intracellular Ca2+ Oscillations, Initiated by the Activation of IP3 Receptors

Intracellular Ca²⁺ Oscillations, Initiated by the Activation of IP₃ Receptors