Effects of hexasulfobutylated C₆₀ on the gastric circular muscle of guinea pig

The effects of hexasulfobutylated (FC₄S), the fullerene derivative on the contraction of smooth muscle were tested pharmacologically on the circular muscle of stomach of guinea pigs. The effects of monomalonic acid C₆₀ (MMA C₆₀) on the same preparations were compared. The effects of those compounds on the taenia coli, portal vein and vas deferens of guinea pigs were also tested. The FC₄S did, while MMA C₆₀ did not elicit contracture of the circular muscle of stomach and taenia coli. Both FC₄S and MMA C₆₀ did not elicit contraction on the portal vein and on the vas deferens of the guinea pig. Prazosin (0.5 μM) or propranolol (0.5 μM) did not alter the FC₄S elicit contracture of the circular muscle of stomach. However, atropine (0.01, 0.1 and 1 μM), tetrodotoxin (0.1 μM) or low calcium medium decreased reversibly the FC₄S elicited contracture of the circular muscle of stomach. The effect of FC₄S on the contracture of the gastric muscles was also tested using various muscarinic receptor subtype antagonists. 4-DAMP (1 μM), muscarinic M3 receptor antagonist, and tropicamide (1 μM), muscarinic M4 receptor antagonist, did not alter the contracture elicited by FC₄S. Pirenzepine (0.1 μM), muscarinic M1 receptor antagonist, and methoctramine (0.25 μM), muscarinic M2 receptor antagonist, significantly decreased the FC₄S elicited contracture of the circular muscle. Atropine (1 μM) or tetrodotoxin (0.1 μM) completely blocked the FC₄S elicited contracture of the circular muscle of stomach. It is concluded that FC₄S elicited contracture of the circular muscle of stomach. The effect may be due to FC₄S acts on the cholinergic cells existed in the gastric muscle and indirectly activating the tetrodotoxin dependent releasing of the transmitters from the cells, then, activating the muscarinice M1, M2 receptors in the muscle eliciting the contractures.