Electrical impedance of the labellar taste hair of the blowfly,Calliphora erythrocephala MG.

Summary The impedance characteristics (resistance and phase angle) were measured of the labellar taste hair of Calliphora erythrocephala by recording the values between the base and tip of intact and tip-amputated hairs of young and old flies.Measurements made at 30 Hz to 20 kHz indicated frequency independent values with changes in phase angle up to about 1 kHz and complete bypassing of the insulating cuticle at 15 to 20 kHz.Measurements made at 0.9 kHz with intact and amputated hairs showed a low change in phase angle and thus a negligible reactive component. Subsequently these values were treated as the resistive component of the impedance. Amputation of the tip always caused a drop in impedance of about 30 MOhm.Calculations based on known morphologic data allowed the conclusion that the measurements of intact hairs at slight dipping of the tip have been made through both channels and not the dendrite-containing channel alone; consequently the pore distad of the dendritic endings must have an electrolytic connection to both channels of the taste hair. Slightly deeper dipping of the hair tip (5 or less) resulted in 4 to 7 MOhm reduced impedance which indicates a second pore or opening in the greater tip region.This work was partially supported by National Science Foundation Grant GB-13500.