ELECTRICAL COUPLING, POTENTIALS, AND RESISTANCES IN OAT COLEOPTILES - EFFECTS OF AZIDE AND CYANIDE

Electrophysiological measurements were made on oat coleoptile (A. sativa L. cv. Victory) parenchyma cells. Both 1 mM potassium cyanide and 1 mM sodium azide cause reductions in cell resting potential and electrical coupling and an increase in the combined tonoplast and plasmalemma resistance. The reduction in coupling is probably attributable to a decrease in current flow through plasmodesmata, resulting from an increase in plasmodesmatal resistance. Potassium cyanide also induces some callose formation within cell walls and this may contribute to the observed reduction in coupling. However, sodium azide does not induce callose formation. Presumably, other processes are involved in the reduction of coupling which are not attributable to callose.