Link between relay and oscillations of cAMP

Excitability pulsatile amplification of suprathreshold cAMP signals 

Such pulsatory amplification of the extracellular cAMP pulse accounts for the phenomenon of relay of cAMP signals observed during aggregation of the amoebae on agar (Robertson Drage, 1975) as well as in experiments in cell suspensions (Roos et al, 1975 see fig. 5.14). Table 5.1 shows that the qualitative and quantitative predictions of the model regarding relay behaviour yield satisfactory agreement with experimental observations. 

When the response of the system (fig. 5.18), measured by the ratio ISm/A) of the maximum intracellular cAMP level at the height of the 

Numerical simulations thus indicate that eqns (5.1) can produce either sustained oscillations or excitable behaviour, in slightly different conditions, i.e. for closely related values of the parameters. Phase plane analysis allows us to determine the conditions in which either phenomenon occurs this analysis further shows that the two behavioural modes are necessarily linked (Goldbeter, Erneux Segel, 1978). The same link between excitability and oscillations (see also Hahn et al, 1974) is 

Relay amplitude maximum relay (s) width (s) cellular cAMP (s) max[cAMP], max[cAMP] [ATP]/[cAMP], 

---