Multifunctional transmembrane-building blocks with recognition sites for adrenaline on one end and the reaction partners for an SN2 reaction on the opposite end have been embedded in DPPC-liposomes. These doped vesicles can be quant. reduced at their disulfide head groups by externally added reducing agents; their compn. and chem. processes taking place within can be monitored by NMR spectroscopy and- with limitations-by UV/Vis spectroscopy. Attempted release of thiopyridine as a second messenger into the interior of the liposome on external adrenaline addn. could not be proven unambiguously because the detection system does not fulfill the necessary rigorous specificity and sensitivity requirements.