Correlation Between Electrophysiology and Radioligand Binding Studies

A good correlation between electrophysiological measurements, using isolated Heliothis neurons, and radioligand binding studies on housefly head membranes regarding the affinity of ligand to wAChRs was found (Fig. 29.1.4). 

This correlation for commercial neonicotinoids 8-13 may indicate that houseflies (binding data) and tobacco budworms (electrophysiology) have similar binding sites for 7 and related compounds. 

Like 7, all neonicotinoids bind with high affinity (I50S 1 mM) to [ H]-7 bind- 

On the other hand, fully antagonistic neonicotmoids have a very limited insecticidal efficacy. This general observation is supported by other investigations that demonstrate the positive correlation between nerve activity induced in cockroach preparations and insectiddal activity of neonicotmoids against green rice leafhop-per (N. cincticeps). 

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