Mechanisms involved in the spasmolytic effect of extracts from sabal serrulata fruit on smooth muscle

• 1.1. The effects of two extracts from Sabal serrulata fruits total lipidic (L) and saponifiable (S)] on smooth muscle contractions have been assayed.
• 2.2. Both extracts (0.1–1 mg/ml) relaxed the tonic contraction induced by norepinefrine (30 nM) on rat aorta EC₅₀, 0.53 ± 0.05 mg/ml (L) and 0.5 ± 0.04 mg/ml (S)] and by KCl (60 mM) on rat uterus. The Sabal extracts (0.3–1 mg/ml) also antagonized the dose-response curve of contractions induced by acetylcholine (0.1–100 μM) on urinary bladder.
• 3.3. dL-Propranolol (1 μM) but not the inactive (R)-(+)-propranolol (1 μM) potentiated the Sabal extracts relaxant effect by lowering the EC₅₀ (0.35 ± 0.2 vs 0.20 ± 0.01 mg/ml for L and 0.43 ± 0.02 vs 0.19 ± 0.02 mg/ml, P < 0.01, for S extract).
• 4.4. Cycloheximide (10 μg/ml) antagonized the effect of extracts from Sabal. However, actinomycin D (5 μg/ml) significantly (P ≤ 0.01) antagonized the effect of the total lipidic extract without modifying that of the saponifiable extract.
• 5.5. The relaxant effect of both extracts was not modified by the tyrosine kinase inhibitor genistein (10 μM) or the ornithine decarboxylase inhibitor α-difluoromethyl-ornithine (10 mM).