Treatment | Ca2+ Fluorescence (%ΔF/F ± SEM) | MEPP Frequency (MEPPs/sec ± SEM) | ||
---|---|---|---|---|
α-LTX (0.5 nm) | 55 ± 9 | (N,n = 9,10) | 340 ± 19 | (N,n = 5,5) |
α-LTX (0.5 nm) after U-73122 (50 μm) | 54 ± 6 | (N,n = 4,7; p = 0.76) | 353 ± 8 | (N,n = 3,3; similar to 0.5 nm α-LTX) |
Thapsigargin (20 μm) | 16 ± 7 | (N,n= 2,3; p = 0.04*) | 3.5 ± 2 | (N,n = 3,3) |
α-LTX (0.5 nm) after thapsigargin (20 μm) | 60 ± 17 | (N,n = 2,3; p= 0.5) | 359 ± 11 | (N,n = 2,2; similar to 0.5 nm α-LTX) |
α-LTX (0.5 nm) after CCCP (10 μm) | 2.4 ± 1 | (N,n = 3,3; p= 0.00005*) | – | |
CCCP (10 μm) | 50 ± 12 | (N,n = 5,5; p= 0.74) | 102 ± 4 | (N,n = 3,3; lower than 0.5 nm α-LTX) |
CCCP (10 μm) after α-LTX (0.5 nm) | 1.3 ± 1 | (N,n = 4,4;p = 0.01*) | – |
The effect of α-LTX (0.5 nm) on Ca2+fluorescence was measured after muscles were incubated with 50 μm U-73122, 20 μm thapsigargin, or 10 μm CCCP in CFS. The effect of 0.5 nm α-LTX on transmitter release was measured after muscles were incubated with U-73122 or thapsigargin. A t test was used to test for significant differences between the peak Ca2+ fluorescence found with 0.5 nm α-LTX alone (control) and the peak Ca2+ fluorescence found with α-LTX applied after a drug, with a drug applied after α-LTX, or with a drug alone. Similarly, qualitative measurements (see Materials and Methods) were made for MEPP frequency (baseline ∼1 MEPP/sec). Data marked with an asterisk indicate statistical significance. N,n, Number of muscles, number of nerve terminals. Transmitter release was not recorded where a dash (–) is indicated. Not all experiments measured fluorescence and MEPP frequency simultaneously.