Physiological research
-
Physiological research · Jan 2004
Cough, expiration and aspiration reflexes following kainic acid lesions to the pontine respiratory group in anesthetized cats.
The importance of neurons in the pontine respiratory group for the generation of cough, expiration, and aspiration reflexes was studied on non-decerebrate spontaneously breathing cats under pentobarbitone anesthesia. The dysfunction of neurons in the pontine respiratory group produced by bilateral microinjection of kainic acid (neurotoxin) regularly abolished the cough reflexes evoked by mechanical stimulation of both the tracheobronchial and the laryngopharyngeal mucous membranes and the expiration reflex mechanically induced from the glottis. ⋯ The pontine respiratory group seems to be an important source of the facilitatory inputs to the brainstem circuitries that mediate cough, expiration, and aspiration reflexes. Our results indicate the significant role of pons in the multilevel organization of brainstem networks in central integration of the aforementioned reflexes.
-
Physiological research · Jan 2004
Hyperoxia attenuated nitrotyrosine concentration in the lung tissue of rats with experimental pneumonia.
Although nitrated proteins have been repeatedly used as markers of lung injury, little is known about their formation and metabolism under hyperoxia. We therefore measured 3-nitrotyrosine (3NTYR) concentrations in lung tissue and serum of rats with carrageenan-induced pneumonia exposed to hyperoxia. Twenty-nine Wistar male rats were assigned to one of 4 groups. ⋯ Carrageenan instillation increased 3NTYR concentrations in lung tissue (carrageenan-normoxic group 147+/-7 pmol/g protein, control 90+/-10 pmol/g protein) and NOx concentration in the serum (carrageenan-normoxic group 126+/-13 ppb, control 78+/-9 ppb). Hyperoxia had no effect on lung tissue 3NTYR concentration in controls (control-hyperoxic 100+/-14 pmol/g protein) but blocked the increase of lung tissue 3NTYR in carrageenan-treated rats (carrageenan-hyperoxic 82+/-13 pmol/g protein), increased NOx in serum (control-hyperoxic 127+/-19 ppb) and decreased serum concentration of 3NTYR in both hyperoxic groups (carrageenan-hyperoxic 51+/-5 pmol/g protein, control-hyperoxic 67+/-7 pmol/g protein, carrageenan-normoxic 82+/-9 pmol/g protein, control 91+/-7 pmol/g protein). The results suggest that hyperoxia affects nitration of tyrosine residues, probably by increasing 3NTYR degradation.
-
Physiological research · Jan 2004
Caffeic acid phenethyl ester improves oxidative organ damage in rat model of thermal trauma.
Severe burn injuries cause functional impairment in distant internal organs. Although this mechanism is not clear, it is possible that free radical toxicity plays an important role. Research in animals and clinical studies have shown that there is a close relationship between a lipid peroxidative reaction and secondary pathological changes following thermal injury. ⋯ Kidney and lung tissues were taken for the determination of malondialdehyde (MDA) level, myeloperoxidase (MPO), catalase (CAT), superoxide dismutase (SOD) and xanthine oxidase (XO) activities. Severe skin thermal injury caused a significant decrease in SOD and CAT activities, as well as significant increases in MDA level, XO and MPO activities in tissues during the postburn period. Treatment of rats with CAPE (10 micromol/kg) significantly elevated the decreased SOD and CAT activities, while it decreased MDA levels and MPO as well as XO activity.
-
Physiological research · Jan 2004
Effects of anesthesia and nociceptive stimulation in an experimental model of brachial plexus avulsion.
Unilateral dorsal rhizotomy of brachial plexus nerves (C5-Th1) performed under general anesthesia is known to induce self-mutilation in rats. The aim of this study was to determine the effect of different anesthetic agents, and of pre-rhizotomy nociceptive stimulation on the appearance of self-mutilation. Self-mutilation appeared in 78% of animals after rhizotomy had been performed under pentobarbital anesthesia. ⋯ Mechanical nociceptive stimulation, when applied just before the induction of ketamine anesthesia and subsequent rhizotomy, provoked self-mutilation in 91% of rats. Furthermore, a serious type of self-mutilation consisting of total amputation of the distal part of the forepaw was present in 28% of all self-mutilating animals after previous nociceptive stimulation. In terms of self-mutilation, these results suggest 1) the crucial role of anesthesia, especially that which involved NMDA receptors (ketamine), and 2) the need of an additional factor to chronic deafferentation, formed either by activity of nociceptive pathways just before rhizotomy (nociceptive stimulation preceding ketamine anesthesia) or by injury discharges (pentobarbital anesthesia).