Browsing by Author "Jovanovic-Micic, D. (6603914795)"

[No abstract available]

Both noradrenaline and clonidine, injected into the cerebral ventricles, induced dose-dependent and shortlasting emesis in cats. Intracerebroventricular yohimbine, but not prazosin, inhibited the emesis evoked by noradrenaline. In contrast, both intracerebroventricular yohimbine and prazosin did not significantly change the clonidine-induced emesis. The ablation of the area postrema impaired the noradrenaline, but not the clonidine-induced emesis. It is postulated that the emesis produced by noradrenaline is mediated through alpha-2 adrenoceptors within the area postrema, whereas clonidine acted on emetic detectors outside chemoreceptor trigger zone in the area postrema most probably within the brainstem areas. These detectors are at least as sensitive to emetic stimuli as those within the area postrema. Moreover, chemical stimuli originating from the cerebrospinal fluid can induce emesis through these detectors without the area postrema.

Effects of the gaglionic stimulants, nicotine, dimethylphenylpiperazinium and tetramethylammonium on the isolated strips of longitudinal and circular muscles from the body of human and feline stomach were investigated. Tetramethylammonium produced concentration-dependent contractions of isolated preparations of either longitudinal or circular muscles of both species. Nicotine induced concentration-dependent relaxation only of the feline circular muscle strips. On the other hand, dimethylphenylpiperazinium had no significant effects on isolated strips of the longitudinal and circular muscles from the body of human and feline stomach. The differences in the effects of the ganglionic stimulants most probably reflect distinct anatomical sites of actions as well as nicotinic and muscarinic receptors in nervous structures and possibly smooth muscles of the human and feline gastric body. In addition, the ability of nicotine, but not of dimethylphenylpiperazinium and tetramethylammonium, to relax only the circular strips of the feline gastric body might indicate the existence of an unusual subtype of nicotinic receptors through which nicotine stimulates the inhibitory enteric ganglia.

[No abstract available]

The effect of tropisetron and morphine injected intravenously upon emesis caused by oral copper sulphate was investigated in unanaesthetized cats. Morphine, but not tropisetron, inhibited the emetic response to copper sulphate. Only the inhibition of percentage of cats showing emesis was dose-dependent. The most sensitive to the inhibitory effect of morphine was number of vomits. These results suggest that morphine might be a putative central inhibitory neurotransmitter, although its peripheral effect cannot be excluded with certainty. In addition, the present experiments support the view that morphine is a broad spectrum antiemetic drug.