Inhibition of (-) [125I]-iodocyanopindolol binding to rat lung beta adrenoceptors by uremic plasma ultrafiltrates.
Numerous data have suggested that beta-adrenoceptor-mediated responses were decreased in uremia and that parathormone could be implicated in this phenomenon. In a previous paper we have shown that the beta2 receptor density of mononuclear cells of uremic patients is significantly increased despite a significant increase in plasma epinephrine, suggesting that an endogenous substance could interfere and disregulate the beta 2 receptor density. In order to further evaluate this phenomenon we have firstly studied the influence of one non uremic and five uremic plasma ultrafiltrates on the binding of (-)-[125I]iodocyanopindolol using rat lung beta adrenoceptors. The results show that uremic plasma ultrafiltrates induce a decrease in the Bmax value without any variation on the Kd value. In a second step we have assessed the ability of human synthetic 1-34 and 53-84 parathormone to interact directly with beta-adrenoceptors. No variation in the (-)-[125I]iodocyanopindolol binding parameters was observed. These results suggest that an uremic endogenous substance might interfere on the beta adrenergic receptors and that the alteration in the beta-adrenergic response in uremia is probably not due to a direct action of parathormone on the beta-adrenoceptors.
Bree
F
F
Laboratoire de pharmacologie, Faculté de Médecine, Creteil, France.
Souchet
T
T
Baatard
R
R
Fontenaille
C
C
Lhoste
F
F
Tillement
J P
JP
D000818:Animals; D006801:Humans; D066298:In Vitro Techniques; D007457:Iodine Radioisotopes; D020120:Iodocyanopindolol; D007700:Kinetics; D008168:Lung / Q000378:metabolism; D008297:Male; D010281:Parathyroid Hormone / Q000097:blood; D010869:Pindolol / Q000031:analogs & derivatives* / Q000378:metabolism; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D014462:Ultrafiltration; D014511:Uremia / Q000097:blood*
D007457:Iodine Radioisotopes; D010281:Parathyroid Hormone; D011943:Receptors, Adrenergic, beta; D020120:Iodocyanopindolol; D011433:Propranolol; D010869:Pindolol