Table II.
Relative frequencies of activity of the three anion conductances in protoplasts prepared from the xylem parenchyma of roots of barley
| Conductance Type | [Ca2+] in the Pipette
|
|
|---|---|---|
| 0.15 μm | 5 μm | |
| % | ||
| X-IRAC | 11** (9 out of 84) | 34** (25 out of 74) |
| X-QUAC | 27* (16 out of 59) | 10* (7 out of 68) |
| X-SLAC | 7 (7 out of 104) | 0 (0 out of 68) |
Percentage of protoplasts in which the respective conductance was active at a low and a high intracellular concentration of Ca2+. Absolute numbers of protoplasts investigated are given in parentheses. The activities of X-IRAC and X-QUAC were significantly correlated with the internal Ca2+ concentration (χ2-test, *, P = 0.05, **, P = 0.005). Determinations of X-QUAC and X-IRAC were made in external standard solution. Data on the activity of X-SLAC included measurements with external 1 and 40 mm Ca2+. If data obtained solely with external standard solution were considered, X-SLAC was active in four out of 59 protoplasts, which again resulted in a percentage of 7.