Membrane and action potential parameters of type 1 and type 2 Dahlgren cells from seawater- and freshwater-adapted caudal neurosecretory systems
| . | Type 1 Dahlgren cells . | . | Type 2 Dahlgren cells . | . | ||
|---|---|---|---|---|---|---|
| . | SWA . | FWA . | SWA . | FWA . | ||
| Membrane parameters | ||||||
| Resting membrane potential (mV) | −61.4±1.5 (25) | −60.8±1.5 (18) | −60.3±1.6 (7) | −62.3±2.8 (3) | ||
| Input resistance (Mω) | 25.6±1.9 (12) | 32.1±3.9 (15) | 24.1±1.6 (7) | 21.1±3.1 (3) | ||
| Action potential parameters | ||||||
| Threshold (mV) | −49.7±1.8 (12) | −48.2±1.3 (18) | −44.2±1.1 (7) | −45.9±0.5 (3) | ||
| Amplitude (mV) | 89.9±2.0 (21) | 92.0±1.8 (18) | 68.6±2.7 (7) †† | 75.0±1.0 (3) ††† | ||
| Duration (ms) | 4.3±0.1 (9) | 3.5±0.2 (6) * | 4.5±0.2 (7) | 3.4±0.1 (3) * | ||
| Afterhyperpolarisation amplitude (mV) | 11.9±0.9 (21) | 12.7±0.5 (18 | 7.5±0.6 (7) † | 8.7±0.6 (3) ††† | ||
| Afterhyperpolarisation duration (ms) | 209.8±20.0 (21) | 217.6±19.2 (18) | 36.6±2.5 (7) †† | 32.0±2.5 (3) ††† | ||
| . | Type 1 Dahlgren cells . | . | Type 2 Dahlgren cells . | . | ||
|---|---|---|---|---|---|---|
| . | SWA . | FWA . | SWA . | FWA . | ||
| Membrane parameters | ||||||
| Resting membrane potential (mV) | −61.4±1.5 (25) | −60.8±1.5 (18) | −60.3±1.6 (7) | −62.3±2.8 (3) | ||
| Input resistance (Mω) | 25.6±1.9 (12) | 32.1±3.9 (15) | 24.1±1.6 (7) | 21.1±3.1 (3) | ||
| Action potential parameters | ||||||
| Threshold (mV) | −49.7±1.8 (12) | −48.2±1.3 (18) | −44.2±1.1 (7) | −45.9±0.5 (3) | ||
| Amplitude (mV) | 89.9±2.0 (21) | 92.0±1.8 (18) | 68.6±2.7 (7) †† | 75.0±1.0 (3) ††† | ||
| Duration (ms) | 4.3±0.1 (9) | 3.5±0.2 (6) * | 4.5±0.2 (7) | 3.4±0.1 (3) * | ||
| Afterhyperpolarisation amplitude (mV) | 11.9±0.9 (21) | 12.7±0.5 (18 | 7.5±0.6 (7) † | 8.7±0.6 (3) ††† | ||
| Afterhyperpolarisation duration (ms) | 209.8±20.0 (21) | 217.6±19.2 (18) | 36.6±2.5 (7) †† | 32.0±2.5 (3) ††† | ||
SWA, seawater adapted; FWA, freshwater adapted.
Values are means ± s.e.m. (number of cells).
Only spike duration was significantly different between SWA and FWA cells.
*Significant differences between type 1 or type 2 cells from SWA versus FWA preparations; *P<0.02.
†Significant differences between type 1 and type 2 cells from the same adaptation state; †P<0.02, ††P=0.01, †††P<0.01.