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SHR Neuro Cancer Cardio Lipid Metab Microb
Boltz, A; Schmidl, D; Werkmeister, RM; Lasta, M; Kaya, S; Palkovits, S; Told, R; Frantal, S; Garhöfer, G; Schmetterer, L.
Role of endothelin-A receptors in optic nerve head red cell flux regulation during isometric exercise in healthy humans.
Am J Physiol Heart Circ Physiol. 2013; 304(1):H170-H174
Doi: 10.1152/ajpheart.00408.2012
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- Co-authors Med Uni Graz
- Palkovits Stefan
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- Abstract:
- Endothelin-1 (ET-1) is an important regulator of vascular tone in the eye. It appears to play a role in ocular disease because of its strong vasoconstrictor action, its role in intraocular pressure homeostasis, and its neurotoxic potential. We have previously shown that ET-1 is involved in choroidal red cell flux (RCF) regulation during isometric exercise in healthy humans. In the present study we hypothesized that ET-1 also plays a role in optic nerve head (ONH) RCF regulation during isometric exercise. To test this hypothesis, we performed a randomized, double-masked, placebo-controlled, two-way crossover study in 15 healthy volunteers. Subjects were randomized to receive intravenous infusions of the specific endothelin type A receptor antagonist BQ-123 and placebo on two different study days. During these infusion periods, subjects performed squatting for 6 min to increase ocular perfusion pressure (OPP). ONH RCF was assessed with laser-Doppler flowmetry, and OPP was calculated from mean arterial pressure and intraocular pressure. BQ-123 did not change OPP or ONH RCF at baseline. The relative increase in OPP during isometric exercise was comparable between both groups (between 84 and 88%, P = 0.76 between groups; P < 0.001 vs. baseline). Isometric exercise increased ONH RCF during placebo and BQ-123, but the increase was more pronounced when the endothelin type-A receptor antagonist was administered (placebo, 27.3 ± 5.4%; and BQ-123, 39.2 ± 4.4%; P = 0.007 between groups). The present data indicate that ET-1 regulates red cell flux in the ONH beyond the autoregulatory range.
- Find related publications in this database (using NLM MeSH Indexing)
- Adult -
- Arterial Pressure -
- Arterial Pressure -
- Cross-Over Studies -
- Double-Blind Method -
- Endothelin-1 - metabolism
- Erythrocytes - drug effects
- Exercise -
- Female -
- Heart Rate -
- Humans -
- Infusions, Intravenous -
- Intraocular Pressure -
- Isometric Contraction -
- Laser-Doppler Flowmetry -
- Male -
- Optic Disk - blood supply
- Peptides, Cyclic - administration & dosage
- Receptor, Endothelin A - antagonists & inhibitors
- Time Factors -
- Young Adult -
- Find related publications in this database (Keywords)
- optic nerve head red cell flux
- isometric exercise
- endothelin
- human