1 The actions of the opiate receptor drugs, morphine, methionine-enkephalin (Met-enkephalin) and naloxone were compared with the actions of the cr2-receptor drugs, clonidine, xylazine and yohimbine on analgesic tests, in vitro bioassay (guinea-pig ileum and mouse vas deferens), and radioligand displacement studies on rat brain membrane preparations. 2 Both opiate and c2-agonist drugs showed analgesic activity but whilst the a2-agonist analgesic activity was antagonized by only C2-antagonists, the analgesic activity of morphine was antagonized by both naloxone and yohimbine. In the in vitro tests, both groups of agonists inhibited electrically evoked activity; however in these experiments only antagonism of opiates by naloxone and M2-agonists by yohimbine could be shown and it is concluded that in these systems the activity of the CX2-agonists is mediated via the presynaptic C2-receptors only. 3 In the radioligand studies the drugs acting at a2-receptors were active in the micromolar range at displacing labelled opioid ligands but opiates did not displace labelled a2-ligands. 4 It is concluded that drugs which act on a2-receptors interfere with the in vivo analgesic effects of opiates and weakly displace opioid radioligand binding, but opioids do not affect a2 agonist analgesia and do not appear to displace c2-agonist radioligand binding.
Food poisoning is encountered throughout the world. Many of the toxins responsible for specific food poisoning syndromes are no longer limited to isolated geographic locations. With increased travel and the ease of transporting food products, it is likely that a patient may present to any emergency department with the clinical effects of food poisoning. Recognizing specific food poisoning syndromes allows emergency health care providers not only to initiate appropriate treatment rapidly but also to notify health departments early and thereby prevent further poisoning cases. This article reviews several potential food-borne poisons and describes each agent's mechanism of toxicity, expected clinical presentation, and currently accepted treatment.
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