A receptor’s subunit composition can influence how it responds to both its natural transmitter and a drug. Researchers examined that relationship by expressing selected human GABA-A receptor combinations in frog egg cells and measuring electrical currents.
The team varied the epsilon, theta and gamma-2 subunits in receptors containing alpha-3 and beta-1. GABA sensitivity differed substantially across combinations. Adding epsilon also reduced modulation by several tested drugs, including flurazepam, under the experimental conditions. The response to pentobarbital followed a different pattern.
The experiment isolates properties of specified receptor combinations. It leaves their distribution in an individual brain, drug exposure at the receptors, and whole-person effects unresolved. A receptor-level result can help explain why responses vary, but it cannot establish an impairment threshold from a blood concentration.