In this study, effects of Buthus eupeus venom on chick biventer cervices nerve-muscle preparation were investigated by twitch tension method. The venom, at 1.3 ?g/ml, increased contractile responses in indirect stimulations. These effects were milder in direct muscle stimulations. It also caused significant enhancement in postjunctional sensitivity as assessed by responses to exogenous acetylch...

Antibody against acetylcholine receptor induces an increase in the rate of degradation of acetylcholine receptors on a mouse cell line (BC(3)H-1) and cultured rat skeletal muscle. The increased rate of degradation results in a lowered density of acetylcholine receptors on muscle membrane and a lowered sensitivity to iontophoretically applied acetylcholine. The modulation of acetylcholine recept...

Nicotine is a drug of abuse that presumably exerts its psychoactive effect through its interactions with nicotine binding sites in the central nervous system. Among its potential sites of action are the neuronal nicotinic acetylcholine receptors and the neuronal alpha-bungarotoxin binding sites. In this review we focus on the neuronal nicotinic acetylcholine receptors, their diversity, distribu...

Anticholinergics are widely used for the treatment of COPD, and to a lesser extent for asthma. Primarily used as bronchodilators, they reverse the action of vagally derived acetylcholine on airway smooth muscle contraction. Recent novel studies suggest that the effects of anticholinergics likely extend far beyond inducing bronchodilation, as the novel anticholinergic drug tiotropium bromide can...

We have studied the role of M(2) and M(3) muscarinic receptors in acetylcholine-mediated desensitization of the contractile response to histamine in the guinea pig ileum. Treatment of the isolated ileum with acetylcholine (30 microM) for 20 min caused a marked desensitization of the contractile response to histamine. When measured 5 min after washout of acetylcholine, the EC(50) value of histam...