Table II.

Tonoplast and plasma membrane L_P required to fit the pressure relaxations of individual cortical cells from wheat roots

Cell No.	Control			HgCl2
	×LPt	×LPp	Kinetics	×LPt	×LPp	Kinetics
237	1	1.18	s	0.25	0.65	d
58	1	5.50	s	0.20	1.80	d
287a	1	1.35	s	0.30	0.50	s
287b	1	5.00	s	0.20	1.40	d
1412	1	2.30	s	0.30	1.60	d
297	3	10.0	s	1.50	1.40	s

The three-compartment model of Wendler and Zimmerman (1985) was used, and the starting values of the tonoplast and plasma membrane L_P were set at those obtained for isolated membrane vesicles from wheat roots of similar age obtained by Niemietz and Tyerman (1997). The values presented in the table are the multiplying factors used on the Niemietz and Tyerman (1997) L_P values to obtain a good fit for each cell. L_P^t, 6.3 × 10⁻⁷ m s⁻¹ MPa⁻¹; L_P^P, 9.2 × 10⁻⁸ m s⁻¹ MPa⁻¹. Also given is whether the kinetics of the pressure relaxation were best fit by a single- (s) or double-exponential (d) equation. The other parameters for fitting to the model were set to the values measured with the pressure probe on the individual cells, assuming that the cytoplasm was 2 μm in thickness.