Response to extracellular stimuli lab report discussion

Cells treated with different stimuli demonstrate different patterns of cytosolic calcium fluctuations due to the nature of the stimuli interaction with the cell. ATP stimulated cells demonstrate oscillatory calcium concentrations due to the negative feedback loops of the signaling pathway that allow calcium influx and export to be halted and resumed on a continuum. Bradykinin stimulated cells are stimulated by G-protein receptors, which when stimulated commence a signaling cascade which opens calcium ion channels on the plasma membrane of the cell. The nature of G-protein coupled receptors can be variable with respect to response, so this delayed and segmented response of fluo-4 is expected. Vasopressin stimulated cells exhibited no change in cytosolic concentration over time, despite common scientific literature stating an oscillatory response is expected. This lack of response in the cells to vasopressin could be due to insufficient time of cells observed, in which the cytosolic calcium did in fact fluctuate, but later in time and was not visualized in the time lapse. Another reason for this disappearance in fluo-4 intensity fluctuation could be due to inadequate addition of the vasopressin stimulus, so that cells were unable to react to the vasopressin.