Lymphocyte beta 2-adrenoceptors mirror precisely beta 2-adrenoceptor, but poorly beta 1-adrenoceptor changes in the human heart.
To study the relationship of changes in human lymphocyte beta-adrenoceptors to changes potentially occurring in solid tissues we studied 16 patients undergoing elective coronary artery bypass grafting and determined the density of lymphocyte beta 2-adrenoceptors [by (-)125I-iodocyanopindolol (ICYP) binding] in comparison to beta-adrenoceptor density and responsiveness (contractile responses to isoprenaline) in the corresponding right atria. Lymphocyte beta 2-adrenoceptor density (with a range of 278-2442 ICYP binding sites/cell) was significantly correlated with beta-adrenoceptor density in the corresponding atria (54.8-171.6 fmol ICYP bound/mg protein, r = 0.784, P less than 0.001). In these atria the levels of beta 1- and beta 2-adrenoceptors (assessed by non-linear regression analysis of competition curves of the selective beta 2-adrenoceptor antagonist ICI 188,551 with ICYP binding) were approximately .70 and 30%, respectively. Lymphocyte beta 2-adrenoceptor density, however, correlated significantly better with atrial beta 2-adrenoceptor (r = 0.8441; P less than 0.001) than beta 1-adrenoceptor (r = 0.6226, P less than 0.05) density. On 12 of the 16 atria (electrically driven with 1 Hz at 37 degrees C) isoprenaline (10(-9) to 3 X 10(-6) mol/l) caused positive inotropic effects. The maximum increase in contractile force evoked by saturating concentrations of isoprenaline (mean: 3.52 +/- 0.62 mN), however, correlated equally well with beta 1- and beta 2-adrenoceptor density in the corresponding atria (r = 0.6834 and 0.6567, respectively). These results indicate that changes in lymphocyte beta 2-adrenoceptors can be taken as a precise index of changes of beta 2-adrenoceptors in other (solid) tissues; beta 1-adrenoceptor alterations, however, are only poorly reflected in the lymphocytes.
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000328:Adult; D000368:Aged; D005260:Female; D006325:Heart Atria; D006801:Humans; D020120:Iodocyanopindolol; D007545:Isoproterenol / Q000494:pharmacology; D008214:Lymphocytes / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000378:metabolism*; D010869:Pindolol / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors / Q000378:metabolism; D011412:Propanolamines / Q000494:pharmacology; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*
D000319:Adrenergic beta-Antagonists; D011412:Propanolamines; D011943:Receptors, Adrenergic, beta; C026777:ICI 118551; D020120:Iodocyanopindolol; D010869:Pindolol; D007545:Isoproterenol