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Eur J Appl Physiol. 2011 Mar;111(3):531-7. doi: 10.1007/s00421-010-1668-3. Epub 2010 Oct 6.

Modulation of plasma adrenomedullin by epinephrine infusion during head up tilt.

Author information

1
Institute of Physiology, Center of Physiological Medicine, Medical University of Graz, Harrachgasse 21/5, 8010, Graz, Austria.

Abstract

We investigated whether head up tilt (HUT) with and without simultaneous epinephrine infusion modulate plasma adrenomedullin. We studied eight healthy male volunteers, using two 5 min 70° HUT trials: control (saline infusion) and intervention (epinephrine infusion, titrated to a dose which increased supine systolic pressure by 20% above resting values). Protocols were randomized and separated by 2 weeks. Cardiac function and systolic time intervals, recorded using a phonocardiograph microphone, included left ventricular ejection time (LVET), pre-ejection period (PEP), PEP/LVET and electromechanical systole (QS2). Compared to saline infusion, epinephrine increased supine adrenomedullin (3.2 ± 0.8 pmol/l, i.e., mean ± SEM, respectively), heart rate (HR) (+11.3 ± 2.6 bpm), systolic pressure (+18.4 ± 2.6 mmHg) but decreased supine LVET, LVET corrected for HR (LVETi) and QS2-time (all p = 0.004). Despite similar HUT induced thoracic fluid shifts, reflected by similar thoracic impedance changes, HUT-induced adrenomedullin increases were minimal in epinephrine-supplemented men in comparison to controls (+8% vs. 42%). During HUT, epinephrine infusion decreased only the LVET (p = 0.039). Our findings confirm that short-term HUT increases plasma adrenomedullin. They further suggest that with increased supine epinephrine levels (epinephrine infusion clamping systolic arterial pressure at 120% control level), supine cardiac performance rises to a level similar to that during HUT, while adrenomedullin is still elevated with HUT. This might be in accordance with a 'dampening' role of adrenomedullin during catecholaminergic cardiovascular stimulation. As epinephrine is used as a drug to treat cardiac arrest and ventricular arrhythmias, our results may have important clinical/emergency resuscitation applications.

PMID:
20924597
DOI:
10.1007/s00421-010-1668-3
[Indexed for MEDLINE]

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