TABLE 5.
acaA− cells respond to a rapid increase in cAMP by a reduction in velocity but require a higher concentration of cAMP than control cells for a normal responsea
| cAMP concn | Cell type | No. of cells | Instantaneous velocity before addition (μm/min) | Instantaneous velocity after addition (μm/min) | % Decrease in instantaneous velocity |
|---|---|---|---|---|---|
| 10−6 M | JH10 | 9 | 7.2 ± 1.2 | 3.1 ± 1.2 | 56 |
| acaA− | 19 | 7.2 ± 1.9 | 5.3 ± 1.6 | 26 | |
| acaA− (r) | 7 | 7.7 ± 1.8 | 6.0 ± 1.3 | 21 | |
| 10−5 M | JH10 | 4 | 6.2 ± 0.8 | 3.2 ± 0.4 | 49 |
| acaA− | 5 | 8.8 ± 2.9 | 4.7 ± 1.1 | 45 |
a
Cells were first perfused for 5 min with buffered salts solution alone in a round perfusion chamber. Perfusion solution was then switched to buffered salts solution plus chemoattractant at the concentration indicated. The velocities were averaged for each individual cell over a 5-min period before addition of chemoattractant and a 5-min period after its addition.