r is comprised of many multiple membrane components a receptor/recognition site (R) , agonist and antagonist binding sites, N component a protein heterotrimer which links (R) to the third component, the second messenger (Ni linkage to catalytic moiety of Adenylate Cyclase). The intact system, these multiple components of receptor/effector system are in dynamic steady state influenced by factors such as amount of agonist present, pH, temperature and the prevalence of certain nucleotides and metal ions. In radioligand binding studies carried out in subjects presumed not to have affective disorders an antagonist tritiated rauwolscine was used, this radioligand labels affinity states for the 2 receptor more efficiently than an agonist. High affinity component of rawoulscine binding is the free R (2 (L) affinity state) in contrast low affinity component of rawoulsine binding is R-Ni complex(2 (H) affinity state) this measures the total number of receptor binding sites of both R and R-Ni in the membrane. The ratio’s of the number of free R relative to ‘coupled’ R-Ni sites 2(L)/ 2(H). Multi affinity state ratio reflects the efficiency of receptor coupling, higher ratio’s of R/R-Ni suggest 2 receptor recogition protein is less efficiently coupled to the second messenger.Patients with affective disorders in particular PTSD radioligand saturation studies and competition studies were carried out. Saturation studies demonstrated fewer total platelet 2 adrenergic receptor binding sites in PTSD than in control. A computer analysis of the data exhibited multiple components of rawoulscine saturation and two sites of interaction for both control and PTSD were displayed(2(H) and 2 (L)). The decrease in the number of rauwolscine binding sites was due to fewer 2(H) in the PTSD subjects. Consequently the affinity state ratio was also much higher in PTSD...
