Adrenomedullin inhibits spontaneous and bradykinin‐induced but not oxytocin‐ or prostaglandin F_2α‐induced periodic contraction of rat uterus

In isolated rat uterine strips, adrenomedullin (AM) inhibited the spontaneous periodic contraction in a concentration‐dependent manner (IC₅₀=22.3±0.7 nM). The inhibitory effect of AM was prevented by either AM_22–52, a putative antagonist for AM receptors, or calcitonin gene‐related peptide (CGRP)_8–37, a putative antagonist for CGRP receptors. AM also attenuated bradykinin (BK)‐induced periodic uterine contraction, which was blocked by AM_22–52 or CGRP_8–37, whereas AM had no effect on the periodic contraction caused by oxytocin or prostaglandin F_2α (PGF_2α). RT–PCR analysis showed that mRNAs for calcitonin receptor‐like receptor (CRLR), receptor‐activity‐modifying protein (RAMP)1, RAMP2 and RAMP3 were expressed in the rat uterus. These results demonstrate that AM selectively inhibits spontaneous and BK‐induced periodic contraction via activating receptors for AM and CGRP.

British Journal of Pharmacology (2000) 130, 1727–1730; doi:10.1038/sj.bjp.0703500

DOI: 10.1038/sj.bjp.0703500

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