Active alpha 2 and beta adrenoceptors in lymphocytes from patients with chronic lymphocytic leukemia.
A single population of alpha 2 adrenoceptors was characterized in intact B lymphocytes from patients with chronic lymphocytic leukemia (B-CLL) by binding and saturation studies with 3H labelled yohimbine and by competition studies with alpha adrenergic antagonists. While the affinity of B-CLL alpha 2 adrenoceptors was low (KD: 9.81 nM-20.98 nM), each cell expressed a large number of receptors. No binding of the alpha 1 adrenoceptor antagonist prazosin was observed and the binding properties of beta adrenergic receptors (assayed with 3H-labelled dihydroalprenolol), were similar to those described for normal lymphocytes. Reaction of B-CLL with the beta adrenergic agonist isoproterenol raised the levels of cAMP in 11/13 patients tested, and in 8 of these, incubation with the alpha 2 adrenergic agonist clonidine prevented the effect and reduced the basal cAMP levels. The presence of active alpha 2 adrenoceptors on B-CLL lymphocytes may be involved in the regulation of metabolic pathways that affect cell functions and favor neoplastic growth.
Goin
J C
JC
Centro de Farmacología y Botánica CEFYBO, Buenos Aires, Argentina.
Sterin-Borda
L
L
Borda
E S
ES
Finiasz
M
M
Fernández
J
J
de Bracco
M M
MM
D000368:Aged; D000369:Aged, 80 and over; D003000:Clonidine / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D005260:Female; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000378:metabolism*; D008214:Lymphocytes / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D011433:Propranolol / Q000494:pharmacology; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D013696:Temperature; D015016:Yohimbine / Q000378:metabolism
D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D015016:Yohimbine; D011433:Propranolol; D000242:Cyclic AMP; D007545:Isoproterenol; D003000:Clonidine