No abstract

Detailed electromyographic and electrodiagnostic studies were made on sciatic nerve-anterior tibialis muscle preparations in rat in vivo for the first time to confirm the neuromuscular junctional (NMJ) blocking action of Cleistunthus collinus leaf extract (CCLE) and the transient reversal of NMJ blockade by neostigmine. A sublethal dose of 175 mg dry leaf powderkg body weight of rat caused NMJ blockade confirmed by a decremental response in nerve evoked compound muscle action potentials (NCMAPs). The study suggests the action of the toxic plant extract on acetylcholine (ACh) receptor sites. Muscle evoked compound muscle action potentials (MCMAPs)showed negligible decremental response suggesting the action at the NMJ level only and not on muscle excitation and contractility. The CCLE poisoning revealed a specific diagnostic EMG pattern which might be of help to clinicians in diagnosing Cleistanfhus poisoning. The studies confirm that the leaf extract contains a proven and promising new NMJ blocker.

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The effect of acetylcholine, scopolamine, and Dafura leaf and root extracts on the contractility of dispersed muscle ceUs of guinea-pig ileum was studied. Scopolamine and crude Datura leaf extract alone or together had no significant effect on contraction of smooth muscle cells. Acetylcholine and Dafuru root extract either alone or together caused a significant (30%) contraction. Dafura root extract reversed the effect of both scopolamine and Datum leaf extract suggesting the presence of an unknown spasmogenic factor in Dafuru root extract.

The Michaelis-Menten constant (Km) for cholinesterases from different liver sources, the inhibitor concentration for 50% inhibition (I50), and the lower limit of estimation were determined for 3 organophosphorus pesticides and their oxygen analogs. Maximum sensitivity in organophosphorus pesticide determinations can be achieved by choosing the enzyme source which has a higher Km value. An inverse relationship is suggested between Km and the lower limit of estimation.