Possible Mechanism of Antispasmodic Action of Garcinia kola Seed Extract on Isolated Guinea Pig Ileum

Abstract

Aims: Garcinia kola is used in West African countries for the treatment of various ailments such as cough, tooth decay, asthma and menstrual cramps. The inhibitory effect of Garcinia kola seed extract (GKE) on drug-induced contractions was studied on iliac smooth muscle preparations of guinea pig to ascertain the validity of the use of Garcinia kola in traditional medicine and to elucidate its possible mechanism of action. Place and Duration of Study: The study was done in Post Graduate Laboratory, Department of Pharmacology, College of Medical Sciences, University of Calabar, Calabar-Nigeria, between November 2013 and April 2014. Methodology: The antispasmodic influence of GKE (0.02 – 1 mg/ml) on acetylcholine, histamine and potassium chloride -induced contractions were carried out. The effect of GKE in a Ca2+-free Tyrode medium and in the presence of adrenergic antagonists was also investigated. Results: The results revealed that GKE inhibited or attenuated the spasmogenic effects of histamine and potassium chloride in a dose-dependent manner and shifted their log. dose-response curves to the right, with pA2 values of 2.09±0.06 and 3.25±0.07 respectively. Pre-administration of propranolol, prazosin or labetalol had no attenuating influence on the antispasmodic effect of GKE. Iliac smooth muscle responses to cumulative increased [Ca2+] in a depolarizing bathing medium and in a Ca2+- free Tyrode solution were also blocked. Comparative antispasmodic potencies indicated that papaverine and aminophylline were more potent than the extract. Conclusion: These findings suggest that Garcinia kola seed extract acts neither via cholinergic nor adrenergic receptor mediation, but may involve interference with Ca2+ mobilization, thus sharing with papaverine and/or aminophylline similar mechanism(s) of action.