Figure 9.

The predicted dependence of the net unitary Na⁺ (——) and Ca²⁺ (− − −) currents through the VIC channel in the plasma membrane of wheat roots on extracellular Ca²⁺ activity under nonsaline (A) and saline (B) ionic conditions. Curves were derived from a 3B2S model for cation permeation using the parameters given in Table I. A membrane potential of −120 mV was assumed. The extracellular activities were 0.904 mm K⁺, 0.696 mm Ca²⁺, and 0.930 mm (nonsaline) or 72 mm (saline) Na⁺. The cytoplasmic activities were 72 mm K⁺, 100 nm Ca²⁺, and 3.5 mm (nonsaline) or 7.2 mm (saline) Na⁺.