Non-invasive, kinetic measurements of [3H]nitrendipine binding to isolated rat myocytes by condensed phase radioluminescence.
The binding of 3H-labelled drug molecules to membranes of living cells gives rise to photon emission from tryptophan residues at proteinaceous binding sites. This phenomenon, called condensed phase radioluminescence, has been used to measure non-invasively the kinetics of [3H]nitrendipine binding and dissociation on the same samples of cultured beating cardiac myocytes. Signal arose only from bound drug molecules. Binding was monoexponential (tau = 5.5 min) as was dissociation (14.3 min). Preincubating cells with non-radioactive nifedipine reduced the amplitude and rate of [3H]nitrendipine but not of [3H]dihydroalprenolol binding. The potential uses of this phenomenon are discussed.
D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D004082:Dihydroalprenolol / Q000378:metabolism; D005470:Fluorometry; D007700:Kinetics; D049449:Luminescence; D009206:Myocardium / Q000378:metabolism*; D009543:Nifedipine / Q000031:analogs & derivatives* / Q000378:metabolism; D009568:Nitrendipine; D051381:Rats; D014316:Tritium
D014316:Tritium; D004082:Dihydroalprenolol; D009568:Nitrendipine; D009543:Nifedipine