Effects of nimodipine and isradipine on endothelin-1-induced contraction of pregnant rat myometrium

Endothelin-1 at concentrations of 10(-10) to 10(-8) M increased the amplitude and frequency of contractions in isolated pregnant rat myometrium.

• Higher concentrations of endothelin-1 (10(-9) and 10(-8) M) raised the basal tone of the myometrium.
• Pretreatment with 10(-6) M nimodipine or 10(-5) M isradipine significantly reduced the amplitude and duration of contractions induced by endothelin-1.
• The frequency of myometrial contractions increased after treatment with nimodipine and isradipine.
• Neither nimodipine nor isradipine completely inhibited the effects of higher endothelin-1 concentrations on basal tone.
• Phasic activity in the myometrium is inhibited by these calcium channel blockers, while tonic activity remains unaffected.

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