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. 2020 May 13;11:402. doi: 10.3389/fphys.2020.00402

FIGURE 4.

FIGURE 4

α-Adrenergic signals augment myogenic reactivity in vitro. In (A–C), cremaster skeletal muscle resistance arteries isolated from naïve mice were treated for 4 h with either 1 μmol/L phenylephrine or control buffer in vitro. The arteries were then washed and assessed in normal buffer. (A) Arteries treated with phenylephrine possess higher myogenic reactivity than control arteries. Although in vitro phenylephrine treatment (B) does not affect subsequent phenylephrine-stimulated vasoconstriction responses, (C) calcium sensitivity is increased (control diamax: 69 ± 2 μm, n = 10; phenylephrine diamax: 73 ± 3 μm, n = 9). (D) Phenylephrine-stimulated vasoconstriction is abolished in cremaster skeletal muscle resistance arteries isolated from smooth muscle cell-targeted Gq11 knockout mice [sm-Gq11(KO); diamax: 96 ± 10, n = 6], relative to wild-type littermate controls [sm-Gq11(WT); diamax: 83 ± 6, n = 6]. (E) In addition to eliminating phenylephrine responses, smooth muscle cell-targeted Gq11 gene deletion also attenuates myogenic tone [sm-Gq11(WT) diamax: 83 ± 6, n = 6; sm-Gq11(KO) diamax: 88 ± 12, n = 4]. *P < 0.05.