Adrenomedullin is increased by pulsatile shear stress on the vascular endothelium via periodic acceleration (pGz)

Periodic acceleration (pGz) is produced by a platform which moves the supine body repetitively in a headward to footward direction. The imparted motion produces pulsatile shear stress on the vascular endothelium. Pulsatile shear stress on the vascular endothelium has been shown to elicit production of a host of cardioprotective, cytoprotective mediators. The purpose of this study was to ascertain if pGz also enhances production of adrenomedullin (AM) in normal healthy swine. Twelve pigs (weight range 20–30 kg) were anesthetized, intubated and placed on conventional mechanical ventilation. All animals were secured to the motion platform. In one group (pGz) (n = 7) was activated for 1 h, and monitored for an additional 3 h. A control group (CONT) (n = 5) served as time control. Arterial blood gases, hemodynamic measurements, and serum for AM, interleukin 4, 6 and thromboxane B2 (TBXB2) were measured at baseline, immediately after pGz, and 3 h after pGz had been discontinued. There was no significant change from baseline value in IL-4, IL-6 or TBXB2. Mean arterial blood pressure decreased in pGz-treated animals from 115 ± 10 at baseline to 90 ± 8 after 60 min of pGz (p < 0.01). AM levels increase from 776 ± 176 pg/ml baseline to 1160 ± 68 pg/ml immediately after pGz, and remained elevated to 1584 ± 160 pg/ml, 3 h after pGz (p < 0.01 vs. BL). This is the first report of AM-enhanced production using a non-invasive method of increasing pulsatile shear stress on the vascular endothelium. pGz increases production of AM in normal healthy swine. These changes are independent of IL-4, IL-6 or TBXB2 production.