Myocardial beta-adrenoceptors and inhibitory G-proteins in myocardial biopsies and in explanted hearts from patients with dilated cardiomyopathy.
Cardiac beta-adrenoceptors and the alpha-subunits of the inhibitory guanine-nucleotide binding proteins (Gi alpha) were determined in myocardial biopsies and in larger samples of explanted hearts from patients with dilated cardiomyopathy. The myocardium of one non-failing heart was studied for comparison. There were fewer beta-adrenoceptors in right and left ventricular samples from hearts with dilated cardiomyopathy than in the non-failing myocardium. The number of beta-adrenoceptors determined by equilibrium saturation experiments closely correlated with their density as measured by a saturating concentration of the radioligand 125Iodocyanopindolol in myocardial biopsies. Using the 32P-ADP-ribosylation of a 40kDa membrane protein catalyzed by pertussis toxin, an increase of Gi alpha could also be shown in both myocardial biopsies and explanted hearts.
Böhm
M
M
Medizinische Klinik I der Universität München, Germany.
Gierschik
P
P
Schnabel
P
P
Erdmann
E
E
D001706:Biopsy; D002311:Cardiomyopathy, Dilated / Q000378:metabolism / Q000473:pathology*; D015536:Down-Regulation / Q000502:physiology; D019204:GTP-Binding Proteins / Q000032:analysis*; D006321:Heart / Q000294:innervation*; D006801:Humans; D015151:Immunoblotting; D007457:Iodine Radioisotopes; D020120:Iodocyanopindolol; D009206:Myocardium / Q000737:chemistry*; D010869:Pindolol / Q000031:analogs & derivatives; D011869:Radioligand Assay; D011943:Receptors, Adrenergic, beta / Q000032:analysis*
D007457:Iodine Radioisotopes; D011943:Receptors, Adrenergic, beta; D020120:Iodocyanopindolol; D010869:Pindolol; D019204:GTP-Binding Proteins