Dopaminergic agonists, cAMP

Figure 9. Specificity of fi-adrenergic and dopaminergic stimulation of cAMP accumulation. Dispersed parathyroid cells were incubated with the indicated fi-adrenergic or dopaminergic agonists either alone (open bars), with 1 pM (—) propranolol (solid bars), or with 10 pM- a-flupenthixol (stippled bars).

ADTN and other dopamine agonists mimicked this effect which was antagonized by a- and B-flupenthixol, the a-isomer being 100 times more potent. In a similar way, dopamine caused a rapid 20-30-fold increase in cellular cAMP in dispersed bovine parathyroid cells. The potency of a series of dopaminergic agonists and antagonists on adenylate cyclase activity paralleled the effects of these ligands on CAMP accumulation and parathormone secretion (16). It was concluded that bovine parathyroid cells possess dopamine sites which are involved in the control of parathormone secretion. 

D2-R, D3-R agonist [0.5] (ot2A-R, piA-R, NADH-CoQ R) [antagonist w.r.t. Apomorphine, dopaminergic, inhibits cAMP formation,... 

Nonglycosidic positive inotropic drugs can be divided into two main classes those that act via stimulating the synthesis of cyclic adenosine monophosphate (cAMP), such as adrenergic and dopaminergic agonists and those that inhibit the hydrolysis of cAMP, such as phosphodiesterase 3 (PDE3) inhibitors. 

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