Table 1.

Summarised data of twitch, tetanus and repriming period following various treatments

	Treatment set	Twitch peak (%)	Tetanus peak (%)	RP (ms)
1.	Control	100 (3)	100 (3)	4.7 ± 0.3 (3)
	100 μm SNAP	98.4 ± 2.2	99.7 ± 0.9	4.3 ± 0.3
2.	Control	100 (6)	100 (6)	4.6 ± 0.3 (6)
	2 mm SNAP	58.5 ± 5.9*	82.4 ± 4.8*	4.2 ± 0.2
	10 mm DTT	79.4 ± 10.1*†	91.6 ± 3.5*†	(not examined)
3.	Control	100 (7)	100 (6)	4.2 ± 0.2 (6)
	10 mm SNAP	54.2 ± 9.2*	88.3 ± 4.3*	4.3 ± 0.2
	10 mm DTT	86.9 ± 7.8†	101.9 ± 3.0†	4.0 ± 0.3
4.	Control	100 (3)	100 (3)	4.3 ± 0.3 (3)
	100 μm DTDP	69.8 ± 5.5*	95.8 ± 0.4*	4.0 ± 0.0
	5 mm GSH	157.7 ± 5.8*	111.4 ± 5.6	4.0 ± 0.0
	10 mm DTT	99.0 ± 2.4†	91.2 ± 14.9	4.3 ± 0.3
5.	Control	100 (5)		4.2 ± 0.2 (5)
	10 mm H2O2 (5 min)	108.2 ± 4.6	(not examined)	4.2 ± 0.2
6.	Control	100 (9)	100 (9)	4.6 ± 0.3 (5)
	2 mm GSNOdel.	65.2 ± 4.7*	91.2 ± 2.1*	4.4 ± 0.3
	10 mm DTT	89.7 ± 5.4†	96.5 ± 4.5	4.2 ± 0.2
7.	Control	100 (4)	100 (4)	4.5 ± 0.5 (4)
	100 μm GSNOimm.	111.0 ± 6.9	102.3 ± 6.0	4.3 ± 0.6
8.	Control	100 (20)	100 (17)	3.5 ± 0.6 (9)
	2 mm GSNOimm.	81.3 ± 8.7*	84.8 ± 5.5*	3.2 ± 0.6

Data are mean ±s.e.m. values of given parameter after the indicated treatment expressed relative to initial control level prior to any treatment. Fibres given up to three different successive treatments, as indicated in the given group; number of fibres (n) shown in brackets. Twitch and tetanic force in control conditions were 27 ± 4% (n = 57) and 92 ± 2% (n = 48), respectively, of maximum Ca²⁺-activated force (at pCa 4.5). The repriming period (RP), a measure of the AP refractory period, was measured as the minimum interpulse interval between a pair of pulses needed to elicit >50% of maximal incremental increase in twitch size (see Fig. 3C).

^*Significant difference (P < 0.05) between value for indicated treatment relative to initial control level.

^†Value following DTT treatment significantly different from preceding value.