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Updated: Jul 11, 2026
07:51
Mesenteric Artery Contraction and Relaxation Studies Using Automated Wire Myography
Published on: September 22, 2011
Cyclic AMP-independent CGRP8-37-sensitive receptors mediate adrenomedullin-induced decrease of CaCl2-contraction in
Gracious R Ross1, Uma Yallampalli, Chandra Yallampalli
1Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Tex., USA.
Journal of Vascular Research
|September 28, 2007
Summary
Adrenomedullin inhibits vascular smooth muscle contraction by affecting intracellular calcium release, not calcium influx. This action is mediated via a calcitonin gene-related peptide (CGRP) receptor and protein phosphatases.
Area of Science:
- Cardiovascular Physiology
- Endocrinology
- Vascular Biology
Background:
- Adrenomedullin is a peptide hormone with known vasodilatory effects.
- Its precise mechanisms in regulating vascular smooth muscle contraction, particularly concerning calcium handling, require further elucidation.
Purpose of the Study:
- To investigate whether adrenomedullin reduces calcium influx in depolarized endothelium-denuded rat mesenteric arteries.
- To determine the signaling pathways involved in adrenomedullin's effects on vascular contraction.
Main Methods:
- Measurement of CaCl(2)-induced and depolarization-induced contractions in rat mesenteric artery segments.
- Use of receptor antagonists (CGRP(8-37), adrenomedullin(22-52)), adenylate cyclase inhibitor (SQ22536), and protein phosphatase inhibitors (calyculin A, sodium fluoride).
- Assessment of intracellular calcium mobilization using thapsigargin.
Main Results:
- Adrenomedullin reduced CaCl(2)-induced contractions, an effect reversed by CGRP(8-37).
- Adrenomedullin did not inhibit depolarization-induced calcium entry into vascular smooth muscle.
- Adrenomedullin inhibited calcium mobilization from intracellular stores.
- The effects were mediated through protein phosphatases, not the cyclic adenosine monophosphate pathway.
Conclusions:
- Adrenomedullin inhibits vascular contraction via a CGRP receptor and protein phosphatase activation, independent of direct calcium influx modulation.
- Adrenomedullin plays a role in calcium homeostasis by inhibiting intracellular calcium release.
- These findings offer new insights into adrenomedullin's function in vascular smooth muscle.
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