RESUMO
Earlier pharmacological screening showed that siculine syrup (a traditional herbal remedy purported to be useful in the prevention and treatment of sickle cell pain - crises, due to sickle cell anaemia - SCA) had antisickling and analgesic activities as well as antimicrobial and diuretic effects. SCA is an important haemoglobinopathy in Africa and many other communities/countries worldwide, with relatively high morbidity and mortality. The present study was to determine the effects of the extract on various isolated muscle preparations - smooth, skeletal and cardiovascular. Siculine (4-20 microg/mL), like acetylcholine (40-400 microg/mL), contracted the isolated rat uterus concentration dependently. Similar effects were observed with the guinea-pig ileum and rabbit jejunum (2-20 microg/mL). In contrast to these effects, the direct (muscle) and indirect (nerve) stimulations of rat phrenic nerve-diaphragm were relaxed by siculine (4 and 8 microg/mL) and d-tubocurarine (0.8 microg/mL). Siculine also concentration-dependently decreased both the rate and force of contraction of guinea-pig atria and rabbit heart and also resulted in a fall in cat blood pressure in a manner similar to those of acetylcholine. The possible therapeutic and/or toxicological consequences of these effects including the hypotensive activity is noteworthy since siculine syrup is used by the local population for the prevention and treatment of sickle cell pain crises.
