Figure 4. The potentiation of [Ca²⁺]_i oscillations by α-adrenergic agonists.

A: upon the application of NE (1 µM) in the presence of 10 nM ACh [Ca²⁺]_i the onset of oscillations is observed in 55±5,8% of adipocytes, (n = 144). B: upon the application of 10 nM ACh in the presence of 5 µM NE the oscillations arise in 47±6,8% of the cells, all the rest showing either no response or a transient increase in [Ca²⁺]_i, (n = 110). C: upon the application of NE (5 µM) in the presence of 10 nM M₃-cholinergic receptor antagonist (p-F-HHSID) and 10 nM ACh, the transient increase of [Ca²⁺]_i is observed in 73±8,0% of adipocytes, with no periodic modes of Ca²⁺ detected, (n = 150). The transient increase of calcium upon NE application is a classic demonstration of adrenergic receptor activation. D: the onset of fast Ca²⁺-oscillations in 37±5,4% of the cells upon application of 3 µM selective agonist of α₁-adrenergic receptors, Phenylephrine, (n = 185). E: the generation of impulse shaped oscillations in 24±4,4% of the cells upon application of 3 µM Phenylephrine, (n = 115). F: the onset of relaxation type oscillations with long period in 08±3,4% of the cells, (n = 167). G: upon the application of 3 µM Phenylephrine against 1 nM ACh the Ca²⁺ signalling system switches to a new steady state with high values of [Ca²⁺]_i n 07±2,1% of adipocytes, (n = 147). H: the transition to a new steady state with high mean values of [Ca²⁺]_i for the oscillation period occurs in single adipocytes, (n = 18). I: the generation of impulse [Ca²⁺]_i oscillations in 24±5,4% of the cells upon the application of 3 µM selective agonist of α₂-adrenergic receptor, UK-14,304, against 1 nM Ach, (n = 138). In the absence of ACh (control experiment), upon the application of UK-14,304 adipocytes respond with a single impulse increase of [Ca²⁺]_i, but they never respond with oscillations.