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Lactate has long been regarded as one of the key metabolites of mammalian cell cultures. High levels of lactate have clear negative impacts on cell culture processes, and therefore, a great amount of efforts have been made to reduce lactate accumulation and/or to induce lactate consumption in the later stage of cultures. However, there is virtually no(More)
In mice, morphine caused a dose-dependent slowing of the rate of intestinal transit of a charcoal meal. This inhibitory effect of morphine was antagonised by naloxone. Pretreatment with a single dose of morphine did not induce any detectable tolerance to the inhibitory action of a second dose of morphine given 4 h later. However, naloxone was more effective(More)
  • C L Wong
  • 1986
In the present study, intestinal motility was measured by the transit of charcoal meal through the small intestine in mice. Morphine, given subcutaneously, caused a dose-dependent slowing of the rate of intestinal transit. This inhibitory effect of morphine was antagonised by prior subcutaneous administration of naloxone hydrochloride or its quaternary(More)
1. Morphine pretreatment (2.0 mg/kg s.c.) induced no overt tolerance to its antinociceptive effect in mice 3 h later, but enhanced the antagonistic potency of naloxone. 2. Pretreatment with chlorpromazine slightly potentiated the antinociceptive effect of morphine measured 3.5 h later. The antagonistic effect of naloxone was also enhanced. 3. The observed(More)
Pretreatment with phenobarbitone (5.0-20.0 mg/kg, s.c.) did not alter the antinociceptive effect (tail-flick assay) of morphine measured 4.5 h later. However, naloxone was more potent in antagonising this antinociceptive effect in phenobarbitone-pretreated mice than in saline-retreated animals. Concomitant administration of naloxone in the pretreatment(More)
D-Histidine, administered in the 'wthdrawal' phase of morphine addiction, failed to modify the expression of tolerance and physical dependence in mice. L-Histidine, on the contrary, can enhance tolerance and inhibit physical dependence. Whole brain histamine is markedly increased by L-histidine administration, but only minimally by D-histidine. This(More)
  • C L Wong
  • 1987
A 30 s swim in water at 30 degrees C reduced the number of abdominal constrictions produced in mice by i.p. acetic acid. Naloxone antagonised this stress-induced antinociception in the female but not in the male. Orchidectomy altered neither the antinociception nor its insensitivity to naloxone antagonism. However, oophorectomy completely abolished the(More)
  • C L Wong
  • 1984
In the present study, the effects of morphine, a predominant mu-receptor agonist, and nalbuphine, a partial agonist supposedly acting on x-receptors, on intestinal motility were studied. The intestinal motility was measured by the transit of charcoal meal through the small intestine in mice. Morphine caused a dose-dependent slowing of the rate of intestinal(More)
  • C L Wong
  • 1991
Both clonidine and morphine dose-dependently inhibited intestinal transit in mice. This inhibitory effect of clonidine was antagonized by prior administration of yohimbine but not by naloxone, while morphine's effect was antagonized by both yohimbine and naloxone. Morphine pretreatment did not induce any apparent tolerance to the effect of clonidine and(More)
  • C L Wong
  • 1985
In the present study, the effect of histamine agonists and antagonists on morphine antinociception and naloxone antagonism were studied. The antinociceptive effect of morphine and the antagonistic effect of naloxone were measured by the acetic acid-induced abdominal constriction test in mice. It was found that pretreatment with 2-methylhistamine, a(More)