A, representative recordings from BSM strips upon stretch after incubation with either arachidonic acid (AA) or l-methionine (L-Meth; N = 3, n = 8). Abbreviation: Ctrl, control. B, examples of stretch recordings showing small-amplitude contractions (indicated by arrows) during the relaxation phase in strips incubated with l-methionine (N = 3, n = 7). C, analysis of integral force (IF) normalized to the peak force (PF) in strips exposed to TREK-1 modulators and stretch. D, contractility and relaxation of BSM in response to a KCl test. Inset shows a scheme of the measured parameters that were used for statistical analyses. E, normalized values of IF/IP of muscle response to KCl after pharmacological modulation of TREK-1 channels. F, top graph summarizes the maximal slope of the contractile phase of KCl response (Sc) after AA and l-methionine applications; bottom graph includes the slope values for muscle relaxation (Sr).