Main content area

Regulation of calcium influx in Chara: Effects of K+, pH, metabolic inhibition, and calcium channel blockers

Reid, R.J., Smith, F.A.
Plant physiology 1992 v.100 no.2 pp. 637-643
Chara, ion transport, active transport, potassium, pH, metabolic inhibitors, internodes, inorganic ions, calcium, Chara corallina
Measurements were made of 45Ca influx into isolated internodal cells of Chara corallina and also into internodal cells of intact plants. 45Ca influx was closely related to growth. In rapidly expanding internodal cells, the influx was approximately 1.4 nmol m-2 s-1 compared to the influx in mature cells from slow-growing cultures of 0.2 nmol m-2 s-1. Isolated internodal cells had influxes in the range 0.2 to 0.7 nmol but this increased to approximately 2 nmol in high calcium solutions and to 4 nmol m-2 s-1 in high potassium solutions. No significant effects on calcium influx were observed for changes in external pH or for treatments that changed internal pH, except that NH4 Was slightly inhibitory. Severe metabolic inhibition by carbonylcyanide-m-chlorophenylhydrazone stimulated influx, whereas dicyclohexylcarbodiimide had no effect and darkness inhibited influx. La3+ also inhibited influx, but the organic channel blockers nifedipine and bepridil stimulated influx. Verapamil had no effect. The results are generally consistent with voltage regulation of calcium channels as in animal cells.