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Temperature and Doublet Potentiation: Effects of Varied Interspike Interval
Author(s) -
Barnes William Stephen
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.962.10
Subject(s) - isometric exercise , chemistry , long term potentiation , stimulation , analytical chemistry (journal) , materials science , medicine , chromatography , biochemistry , receptor
The addition of two closely spaced pulses (doublets) at the beginning of alow‐frequency train of stimuli has been shown to increase peak isometric tension (PT) and tension‐time integral (TTI). This study examined the effects of cooling on potentiation associated with paired pulses having varied (10–100 ms) interspike intervals (ISIs). Sartorii muscles (60–70 mg) from male R. pipiens were dissected free and mounted vertically in water‐jacketed chambers containing oxygenated (100%) Ringer solution (pH 7.2). Muscles were exposed serially to single (SES) and paired (i.e., doublet; DES) electrical stimulation. DES was adjusted to produce ISIs ranging from 10–100 ms. PT (g/g) was measured via field stimulation with supramaximal square wave pulses (1 ms). At 20°C, PT in response to DES (ISI = 100 ms; PT D ) was elevated when compared to SES (PT S ): 105.7 ± 21.5 v. 79.5 ± 10.0, respectively. Decreasing ISI produced further increases in PT D , with maximum PT D occurring at an ISI of 10 ms: 178.0 ± 34.0 v. 79.5 ± 10.0, respectively. At 10°C, PT S at was increased when compared to 20°C: 120.7 ± 8.1 (10°C) v. 79.5 ± 10.0, respectively. Furthermore, PT D (10°C; ISI = 100 ms) was also elevated when compared to SES (10°C); 196.7 ± 22.5 v. 120.7 ± 8.1, respectively. Decreasing ISI produced additional increases in PT D . However, maximum PT D was developed when paired pulses were actually than 10 ms (i.e., ISI = 40 ms). ISIs < 40 ms failed to produce further increases in PT D . Calculated values for TTI (g·s) were similarly affected. These results suggest that: 1) the potentiating effect of paired stimulation is temperature‐sensitive, and 2) the efficacy of paired stimulation in vivo , as a potential neural control strategy to augment force production, may be mediated by environmental factors.