Cardiovascular Diseases Poster Session



Materials & Methods


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Contractile Mechanisms and Peroxide Sensitivity of Endothelin Receptor Subtypes.

Elmoselhi, AB (Department of Medicine, McMaster University, Canada)
Samson, SE (Department of Medicine, McMaster University, Canada)
Grover, AK (Department of Medicine, McMaster University, Canada)

Contact Person: Adel B Elmoselhi (elmosel@fhs.csu.mcmaster.ca)


Endothelins (ETs) bind to two types of receptor: ETA and ETB. We examined the ET receptor types in the pig coronary artery smooth muscle, contractions they produced, their Ca2+- pool utilization and peroxide sensitivity. In Ca2+-containing solution, ET-1 (a non-selective agonist) and IRL1620 (selective ETB agonist) contracted the de-endothelialized rings but the contractions with IRL1620 were much smaller. In Ca2+-free solution, ET-1 contractions were decreased much greater than IRL1620. Treating the rings with peroxide inhibited the contractions produced by both the agents with the following IC50 values in mM: ET-1 in Ca2+ 1.2, ET-1 in Ca2+-free 1.4, IRL1620 in Ca2+ 0.24, and IRL1620 in Ca2+-free 0.14. Pretreating microsome with peroxide did not affect the binding to either receptor types. Cells cultured from this smooth muscle expressed only ETA receptors and ET-1 produced an increase in cytosolic Ca2+. Treating these cells with 0.3 mM peroxide inhibited < 95% of this increased. We conclude that: ETB contractions depend more in intracellular Ca2+- stores than ETA, ETB is more susceptible to peroxide, and ETA mediated Ca2+-mobilization is more susceptible to peroxide than contraction suggesting that ETA contraction has a Ca2+- independent mechanism(s) which is resistant to peroxide. Supported by HSFO.

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Poster Number PAelmoselhi0138
Keywords: Ca2+, Endotholin, Free radicals, Smooth muscle, ET receptor

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Elmoselhi, AB; Samson, SE; Grover, AK; (1998). Contractile Mechanisms and Peroxide Sensitivity of Endothelin Receptor Subtypes.. Presented at INABIS '98 - 5th Internet World Congress on Biomedical Sciences at McMaster University, Canada, Dec 7-16th. Available at URL http://www.mcmaster.ca/inabis98/cvdisease/elmoselhi0138/index.html
© 1998 Author(s) Hold Copyright