| 摘 要： | Aim： To evaluate the impact of extracellular and intracellular Ca2＋ on contractions induced by ethanol in smooth muscle. Methods： Longitudinal smooth muscle strips were prepared from the gastric fundi of mice. The contractions of smooth muscle strips were recorded with an isometric force displacement transducer. Results： Ethanol （164 mmol/L） produced reproducible contractions in isolated gastric fundal strips of mice. Although lidocaine （50 and 100 μmol/L）, a local anesthetic agent, and hexamethonium （100 and 500 μmol/L）, a ganglionic blocking agent, failed to affect these contractions, verapamil （1-50 μmol/L） and nifedipine （1-50 pmol/L）, selective blockers of L-type Ca2＋ channels, significantly inhibited the contractile responses of ethanol. Using a Ca2＋-free medium nearly eliminated these contractions in the same tissue. Ryanodine （1-50 μmol/L） and ruthenium red （10-100 pmol/L）, selective blockers of intracellular Ca2＋ channels/ryanodine receptors; cyclopiazonic acid （CPA; 1-10 μmol/L）, a selective inhibitor of sarcoplasmic reticulum （SR） Ca2＋-ATPase; and caffeine （0.5-5 mmol/L）, a depleting agent of intracellular Ca2＋ stores, significantly inhibited the contractile responses induced by ethanol. In addition, the com- bination of caffeine （5 mmol/L） plus CPA （10 μmol/L）, and ryanodine （10 μmol/L） plus CPA （10 μmol/L）, caused further inhibition of contractions in response to ethanol. This inhibition was significantly different from those associated with caffeine, ryanodine or CPA. Furthermore the combination of caffeine （5 mmol/L）, ryanodine （10 μmol/L） and CPA（IO pmol/L） eliminated the contractions induced by ethanol in isolated gastric fundal strips of mice. Conclusion： Both extracellular and intracellular Ca2＋ may have important roles in regulating contractions induced by ethanol in the mouse gastric fundus.
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