title: Characterization of postsynaptic beta-adrenergic receptors and presynaptic muscarinic cholinergic receptors in the rat spleen.
abstract: The beta-adrenergic and muscarinic cholinergic receptors in the splenic homogenates of control and 6-hydroxydopamine (6-OHDA) treated rats were characterized. The specific binding of [3H]dihydroalprenolol (DHA) and [3H]quinuclidinyl benzilate (QNB) in the rat spleen were saturable and of high affinity and showed pharmacological specificity of splenic beta-adrenergic and muscarinic cholinergic receptors. Following 6-OHDA treatment, the Bmax value for specific [3H](-)DHA binding to the rat spleen was significantly increased by 26 percent and 22 percent compared to control at 2 and 3 weeks without a change in the Kd. In contrast, there was a 38 percent decrease in the Bmax for [3H](-)QNB in the 6-Ohda treated rat spleen at 2 and 3 weeks respectively without a change in the Kd. The Bmax value at 5 weeks was significantly greater than that at 2 or 3 weeks. The splenic norepinephrine (NE) concentration was markedly reduced by the 6-OHDA treatment at 1 to 3 weeks, while there was a significant recovery in the splenic NE concentration at 5 weeks. Thus, our results strongly suggest that we are biochemically localizing muscarinic cholinergic receptors on the sympathetic nerves of the rat spleen and that the beta-adrenergic receptors of the spleen are localized postsynaptically.
mesh_terms: D000526:Alprenolol / Q000031:analogs & derivatives*; D000818:Animals; D004082:Dihydroalprenolol / Q000378:metabolism*; D006892:Hydroxydopamines / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009638:Norepinephrine / Q000378:metabolism; D011812:Quinuclidines / Q000378:metabolism*; D011813:Quinuclidinyl Benzilate / Q000378:metabolism*; D051381:Rats; D011941:Receptors, Adrenergic / Q000378:metabolism*; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D011950:Receptors, Cholinergic / Q000378:metabolism*; D011976:Receptors, Muscarinic / Q000378:metabolism*; D013154:Spleen / Q000294:innervation / Q000378:metabolism*; D013997:Time Factors
chemical_list: D006892:Hydroxydopamines; D011812:Quinuclidines; D011941:Receptors, Adrenergic; D011943:Receptors, Adrenergic, beta; D011950:Receptors, Cholinergic; D011976:Receptors, Muscarinic; D004082:Dihydroalprenolol; D011813:Quinuclidinyl Benzilate; D000526:Alprenolol; D009638:Norepinephrine