Non-specific uptake of the radioligand 125I-IHYP by intact human lymphocytes: Reversal of the uptake process

Abstract

Binding of (±)[125I]iodohydroxybenzylpindolol (IHYP) to β-adrenoceptors on intact human peripheral blood lymphocytes was found to be associated with a high degree of non-specific intracellular uptake of the radioligand. Non-specific binding on cellular surfaces was identified by displacing IHYP from its specific binding sites with the cold competing antagonist (±)-propranolol. Another methodological approach, however, was necessary to eliminate the uptake problem: release of intracellularly accumulated IHYP was achieved by sedimentation of the IHYP-loaded cells and resuspension in hypotonie buffer (HME buffer) for 10 min at + 4°C. The true value of maximal IHYP binding measured after IHYP re..