Effect of ionic environment on the response of the sensory hair of Venus's-flytrap

Abstract

Single cells of multicellular sensory hairs excised from the leaf of Venus's-flytrap were impaled with KCl-filled micropipettes. The cellular resting potential and the electrical response to mechanical stimulation were measured. The effect of changing the ionic composition of the fluid perfusing the hairs was examined by systematically varying the concentration of Na+, K+, Mg2+, Ca2+, Cl−, and H+. The resting potential was only affected significantly and consistently by potassium ion. The amplitude of the resting potential decreased linearly as log [K+] in the perfusing fluid increased. The amplitude of the response potential was affected by all of the ions tested except sodium. Response amplitude decreased linearly as log [K+] for low [K+] and in a more complex fashion for higher [K+]. The amplitude of the response potential increased linearly as log [Mg2+] or log [Ca2+] increased. Changes of [Cl−] and [H+] affected the response potential in a complicated way.