Myenteric plexus-longitudinal muscle preparation

Begg M, Dale N, Llaudet E, Molleman A, Parsons ME (2002) Modulation of the release of endogenous adenosine by cannabinoids in the myenteric plexus-longitudinal muscle preparation of the guinea-pig ileum. Br J Pharmacol 137 1298-1304... 

Z3.3 In Vitro AsKiys for Efficacy. Until the cloning of the opioid receptors isolated tissue preparations, particularly smooth muscle preparations, were used extensively to characterize opioids (see Refs. 131,132 for reviews). The electrically stimulated GPI myenteric plexus-longitudinal muscle and the MVD... 

Electrically stimulated longitudinal muscle/myenteric plexus preparations from guinea-pig ileum (LMMP-GPI)... 

Figure 7.1. The effect of ondansetron on contractile responses to 2-methyl-5-HT in the guinea-pig isolated longitudinal muscle myenteric plexus preparation. Symbols indicate control responses (9) or in the presence of ondansetron at 1 x 10- M (O) or 1 x 10 M ( ). Results + S.E.M. of at least four separate observations. Experiments were performed as described by Butler...

In addition to in vitro cell models, opioid agonists could induce the rapid endocytosis of the receptor in organo cultures or primary neuronal cultures, and also neurons in vivo. Treatment of longitudinal muscle-myenteric plexus preparation or the primary hippocampal neuron cultures with DAMGO resulted in internalization of the mu opioid receptor [146,147]. Similar observation was obtained with fluorescently labeled opioid peptides Fluo-dermorphin and Fluo-deltorphin [148]. Within 15 min of an intra-peritoneal injection of etorphine, mu opioid receptor immunoreactivity was observed in the endosomal structures of the myenteric neurons of guinea pig ileum [149]. Again, rapid clustering of a spliced variant of mu opioid receptor MOR-1C was observed in the lateral septum of the mouse after intracere-... 

Okwuasaba and Cook (1980) dissected the myenteric plexus and longitudinal muscle free of the underlying circular muscle according to the method of Paton (1957), Paton and Zar (1968) and stimulated the preparation with trains of supramaximal rectangular pulses of 1.0 ms duration at a frequency of 0.2 Hz. 

Paton and Zar (1968) described the dissection of the MP-LMP of the guinea-pig small intestine. This preparation has been invaluable in the study of neurotransmission from the myenteric plexus to the longitudinal smooth muscle, particularly by opioids and cannabinoids, without the confounding effects of the peristaltic reflex. A similar preparation has been used to study neuromuscular transmission to the circular smooth muscle (Izzo et al. 1998). Contractions of MP-LMP induced by electrical field stimulation (EES) were potently inhibited in a concentration-dependent fashion by the cannabinoid receptor agonists CP 55,940, CP 50,556, WIN 55,212-2, nabilone, CP 56,667, A -THC and cannabinol (Coutts and Pertwee 1997 Pertwee 2001). This inhibition was competitively and reversibly antagonised by SR141716A, without any effect on the inhibitory responses to normorphine... 

A) Cumulative concentration effect curves to 5-HT in electrically-stimulated longitudinal muscle myenteric plexus preparation from guinea-pig ileum. ( ) Control biphasic concentration effect curve to 5-HT (O) 5-HT after treatment with 10 pM 5-MeOT. Data from [18]. 

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