Low-Frequency (20 kHz) Ultrasonic Modulation of Drug Action

We tested the effect of low-frequency ultrasound (LUS, 20 kHz, 4 W/cm²) on the function of rat mesentery and human pulmonary arteries with wire myography. The vessels were induced to contract with either noradrenaline or physiologic saline solution (PSS) with a high potassium concentration (KPSS) and then incubated with capsaicin (2.1 × 10^-7 M, TRPV1 [transient receptor potential vanilloid 1] activator), dopamine (1 × 10^-4 M, dopamine and α₂-receptor activator), or fenoldopam (dopamine_A1 receptor agonist, 1 × 10^-4 M) with and without glibenclamide (1 μM, KATP [adenosine triphosphate {sensitive potassium channel (ATP)}-sensitive potassium channel] inhibitor and α₂-receptor modulator), and insonated. Vessels were incubated in Ca²⁺-free PSS and induced to contract with added extracellular Ca²⁺ and noradrenaline. Pulmonary arteries were induced to contract with KPSS and dopamine. Then the vessels were insonated. LUS inhibited the influx of external Ca²⁺, inhibited the dopamine-induced vasoconstriction in the KPSS (glibenclamide reversible), reduced the capsaicin-induced vasorelaxation, increased the gentamicin-induced vasorelaxation and increased the dopamine-induced contraction in the KPSS in human pulmonary arteries.