Stimulants ADRs from

Another group of transmitters involved in the control of the cardiovascular system by the autonomous nervous system includes the catecholamines, adrenaline and noradrenaline. In acinar submandibular gland cells of the rat the administration of 10 4 mol/1 adrenaline elicits a reduction in dye coupling from 97 to 75.3% dye-coupled cells [Kanno et al., 1993]. This could not be mimicked with isoprenaline, but was inhibited with phenoxybenzamine. Thus, the uncoupling effect of adrenaline in this preparation is mediated by stimulation of the a-adre-noceptor, whereas a stimulation of the P-adrenoceptor has no effect. 

Flavopiridol was also shown to increase the activity of ATPase in plasma membrane vesicles prepared from a cell line GLC4/ADR which over-expresses multidrug resistance protein (MRP) [26]. The production and activity of MRP is dependent on ATP and so the increase in ATPase activity, stimulated by flavopiridol, reduces the influence of MRP and made the cells more susceptible to cytotoxic agents. 

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