Figure 4. Effects of anesthetics and isoproterenol during the block of G protein and protein kinase A. GDP beta S (trilithium salt; 20 mM shown in panel A) or PKI-(6–22)-amide (10 micro Meter, shown in panel B) were added to the standard pipette solution during all phases of the experiment. The additional reduction of INaby isoproterenol was analyzed from the steady state obtained during anesthetic exposure, as shown by dotted lines. Data were obtained every 15 s from a 30-ms test pulse to -20 mV from a holding potential of -80 mV.