Effects of chronic metoprolol and sulphinpyrazone on human lymphocyte beta-adrenoceptors.

Multiple (100 mg twice daily for 21 days) but not single (100 mg) oral doses of metoprolol significantly reduced the number (Bmax) and the KD of beta-adrenoceptors on intact lymphocytes from nine healthy volunteers. Sulphinpyrazone (400 mg twice daily for 21 days) did not change lymphocyte beta-adrenoceptors and did not modify their reaction to chronic metoprolol. In vitro sulphinpyrazone (10-4M) increased [3H]-DHA specific binding on intact lymphocytes. This effect was not modified by metoprolol, sulphinpyrazone or the two combined. Metoprolol and sulphinpyrazone did not interact in the experimental model of beta-adrenoceptors on intact lymphocytes in conditions mimicking long-term treatment.