Table 2. The buffer molarities used by investigators in non-invasive ion probe studies of biological systems with a computed facilitation factor (DF/TF) of increased proton flux due to that level of buffer at the prevailing or potential pHs.

Buffer

pK

 

molarities, pH

 

DF/TF

 

references

MES

6.15

15 mM, pH 5.5

1 mM, pH 6.0

50 ÁM, pH 6.15

63

22

3

pollen tube growth

pollen tube growth and Ca flux [9]

pollen tube growth and H flux [4]

HEPES

7.55

0.001, pH 8.2

0.001, pH 7.2

1495

230

gastric oxyntic cells [5]

Periplaneta oocytes [10]

Bicarbonate

6.13

0.005, pH 8.2

0.0024, pH 7.8

0.0048, pH 7.8

0.0024, pH 6.13

840

395

789

104

gastric oxyntic cells [5]

Xenopus oocytes [10]

Boric acid

9.14

0.0016, pH 6.0

0.0016, pH 7.0

0.0016, pH 8.0

0.0016, pH 8.2

1

16

1281

2976

pollen tube growth Ca flux [9] and H flux [4]