Table 2.

Isometric tension

Species/Solution	n	A0, mN/mm2	P0, mN/mm2	F0, mN/mm2	Hill Coefficient	pCa50
Dros/Swank	11	4.2 ± 0.3LS LR	2.8 ± 0.4LR	1.4 ± 0.2LS LR	2.36 ± 0.58DR LS LR	6.15 ± 0.07LS
Leth/Swank	10	35.1 ± 3.8DS DR LR	18.1 ± 2.3DS DR	17.0 ± 1.7DS DR LR	0.99 ± 0.06DS	5.60 ± 0.06DS DR LR
Dros/Reedy	9	4.4 ± 0.4LS LR	2.5 ± 0.5LS LR	1.9 ± 0.2LS LR	1.17 ± 0.12DS	6.34 ± 0.10LS
Leth/Reedy	10	60.8 ± 2.9DS DR LS	20.8 ± 3.1DS DR	40.1 ± 3.3DS DR LS	0.88 ± 0.05DS	6.06 ± 0.09LS

All values are means ± SE. A₀, total active isometric tension (pCa 5.0); P₀, passive isometric tension (pCa 8.0); F₀, corrected active isometric tension (F₀ = A₀ − P₀). Graphs of the relationship between isometric tension and calcium concentration from individual fibers were fit with the Hill equation to obtain Hill coefficient and pCa₅₀ values for each fiber, which were then averaged. The n values for both sets of Drosophila Hill coefficients and pCa₅₀ values are 3 fibers less than for the isometric tension values. Superscript letters indicate statistical difference between the four sets of fibers based on one-way ANOVA with Holm-Sidak pairwise multiple comparisons, P < 0.05. DS = Drosophila fibers bathed in Swank solutions; DR = Drosophila fibers bathed in Reedy solutions; LS = Lethocerus fibers bathed in Swank solutions; LR = Lethocerus fibers bathed in Reedy solutions.