PHARMACOLOGY

 RECEPTOR EFFECTOR LINKAGE ::

Although drug receptor interactions explain clearly the mechanism of action of a large number of agents it remains unclear as to how drugs that do not interact with receptors produce identical responses it is also not clear that how a drug interacting with same receptors produces varied effects The research of the last two decades has revealed considerable detail molecular processes that transfer the extracellular signals into intracellular messages Three basic receptor -effector linkages have been clearly identified 

1.Direct regulation of membrane permeability to ions 

2.Regulation of the effect via an intracellular second messenger and /or G-proteins 

3.Regulation of DNA transcription and hence of protein synthesis This may occur by kinase linked receptors on cell membrane or nuclear receptors