Fig. 2. Properties of the K+-induced contraction and the relaxation by washout in PAs and MAs.
(A) Representative original traces showing contractions induced by cumulative increase of [K+]ext in PA and MA. A standard contraction by 80K was commonly induced at the initial phase of each experiment. Note that MA showed more prominent spontaneous relaxation under the raised [K+]ext. (B) Representative original trace of 80K-contraction and the summary of peak amplitude of active tension increase in PAs (n = 16, N = 5) and MAs (n = 10, N = 4). Note the marked difference of the relaxation speed by washout with PSS. (C) The summary of peak amplitudes from PAs and MAs. (D) Summary of the traces of relaxation phase normalized to the peak amplitude of the 80K-contraction (Norm.T/T80K). (E) The 50% and 75% relaxation time to baseline (t1/2 and t3/4, in sec) was measured in each vessel and summarized for the comparison. Data are presented as means ± SD. PA, pulmonary artery; MA, mesenteric artery; PSS, physiological salt solution. **p < 0.01, ***p < 0.001, using two-tailed Student’s t-test.
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