Abstract: In this work, we investigated the spasmolytic effect of caulerpine, a bisindole alkaloid isolated from marine algae of the Caulerpa genus, on guinea pig ileum. Our findings indicated that caulerpine inhibited phasic contractions induced by carbachol (IC50 = 7.0 ± 1.9 × 10−5 M), histamine (IC50 = 1.3 ± 0.3 × 10−4 M) and serotonin (IC50 = 8.0 ± 1.4 × 10−5 M) in a non-selective manner. Furthermore, caulerpine concentration-dependently inhibited serotonin-induced cumulative contractions (pD′2 = 4.48 ± 0.08), shifting the curves to the right with Emax reduction and slope of 2.44 ± 0.21, suggesting a noncompetitive antagonism pseudo-irreversible. The alkaloid also relaxed the ileum pre-contracted by KCl (EC50 = 9.0 ± 0.9 × 10−5 M) and carbachol (EC50 = 4.6 ± 0.7 × 10−5 M) in a concentration-dependent manner. This effect was probably due to inhibition of Ca2+ influx through voltage-gated calcium channels (CaV), since caulerpine slightly inhibited the CaCl2-induced contractions in depolarizing medium without Ca2+, shifting the curves to the right and with Emax reduction. According to these results, the spasmolytic effect of caulerpine on guinea pig ileum seems to involve inhibition of Ca2+ influx through CaV. However, other mechanisms are not discarded.
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Cavalcante-Silva, L.H.A.; de Carvalho Correia, A.C.; Barbosa-Filho, J.M.; da Silva, B.A.; de Oliveira Santos, B.V.; de Lira, D.P.; Sousa, J.C.F.; de Miranda, G.E.C.; de Andrade Cavalcante, F.; Alexandre-Moreira, M.S. Spasmolytic Effect of Caulerpine Involves Blockade of Ca2+ Influx on Guinea Pig Ileum. Mar. Drugs 2013, 11, 1553-1564.
Cavalcante-Silva LHA, de Carvalho Correia AC, Barbosa-Filho JM, da Silva BA, de Oliveira Santos BV, de Lira DP, Sousa JCF, de Miranda GEC, de Andrade Cavalcante F, Alexandre-Moreira MS. Spasmolytic Effect of Caulerpine Involves Blockade of Ca2+ Influx on Guinea Pig Ileum. Marine Drugs. 2013; 11(5):1553-1564.
Cavalcante-Silva, Luiz H.A.; de Carvalho Correia, Ana C.; Barbosa-Filho, José M.; da Silva, Bagnólia A.; de Oliveira Santos, Bárbara V.; de Lira, Daysianne P.; Sousa, Jéssica C.F.; de Miranda, George E.C.; de Andrade Cavalcante, Fabiana; Alexandre-Moreira, Magna S. 2013. "Spasmolytic Effect of Caulerpine Involves Blockade of Ca2+ Influx on Guinea Pig Ileum." Mar. Drugs 11, no. 5: 1553-1564.