Table II.

Initial rates of V-ATPase H⁺ transport and Na⁺/H⁺ exchange activity in tonoplast vesicles isolated from leaves of control and 200 mM NaCl-treated adult M. crystallinum plants treated during a 3-week period, as indicated

Duration	V-ATPase H+ Transport		Na+/H+ Antiport
	Control	NaCl	Control	NaCl
week	% F mg−1 protein min−1
1	668  ± 65	904  ± 46	164  ± 15	215  ± 11
2	693  ± 72	1166  ± 55	161  ± 12	224  ± 15
3	844  ± 40	1614  ± 132	177  ± 17	239  ± 27

Plants were 6 weeks old at the beginning of the experiment. Quinacrine fluorescence assays were performed as described in Methods. Values are means ± sd (n = 3 independent experiments).