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High-altitude pulmonary edema (HAPE) is a common disease observed in climbers, skiers and soldiers who ascend to high altitudes without previous acclimatization. Thus, a reliable and reproducible animal model that can mimic the mechanisms of pathophysiologic response in humans is crucial for successful investigations. Our results showed that exposure to 4500 m for 2 days had little influence on lung function or blood gas, and exposure to 6000 m for 2 or 3 days could change lung function and blood gas, but most parameters returned to nearly normal levels within 48 hours. This study indicates that exposure to 6000 m for 3 days may induce evident lung edema and significantly alter lung function and blood gas, which may mimic HAPE in clinical practice. Thus, this animal model of HAPE may be used in future studies on HAPE. [ABSTRACT FROM AUTHOR]

Representatives of gastropods (Gastropoda), prosobranchs (Prosobranchiata) and pulmonates (Pulmonata), appear in Czech waters. One of the best model spieces for observation in an aquarium is the great pond snail (Lymnaea stagnalis), which are pulmonate (air-breathing) snails. It has a right-coiled shell. It inhabits slow-flowing watercourses, ponds, sand pits, oxbow lakes and pools, as well as wetlands. It feeds on growths (mainly algae), dead and living parts of plants, detritus, and dead animals. This species is hermaphroditic. The eggs are laid in elongated “cocoons” about 5 cm long; the number of eggs is usually around 100. The length of embryonic development varies between 10 and 30 days depending on the temperature. The great pond snail lives 2 to 5 years. The second model species, which is well known to aquarists, is the exotic thermophilic Argentinian spike-topped apple snail (Pomacea bridgesii). It grows to a size of 5–7 cm, and lives up to 5 years, but the life span depends on the temperature in the aquarium – the higher the temperature, the shorter the life. At temperatures below 18 degrees, they are almost inactive. In addition to gill breathing, it also draws atmospheric air with a siphon (air tube), that it pushes to the water surface. The gills are partially transformed into a simple lung sac. The mouth of its shell is closed by a permanent lid (operculum). Feeding the spike-topped apple snail is very easy, as they consume a variety of food as well as feed for aquarium fish. This species is gonochoristic. Females lay eggs above the water in a cluster, up to several centimeters in size. Young snails hatch after 2 to 4 weeks. This paper provides ideas on the methods for breeding and observation, e.g., with regard to the speed of movement, food preference, and the frequency of taking in air on the surface at different water temperatures. [ABSTRACT FROM AUTHOR]

Endogenous and exogenously administered S-nitrosothiols modulate the activities of central and peripheral systems that control breathing. We have unpublished data showing that the deleterious effects of morphine on arterial blood-gas chemistry (i.e., pH, pCO2, pO2, and sO2) and Alveolar-arterial gradient (i.e., index of gas exchange) were markedly diminished in anesthetized Sprague Dawley rats that received a continuous intravenous infusion of the endogenous S-nitrosothiol, S-nitroso-L-cysteine. The present study extends these findings by showing that unanesthetized adult male Sprague Dawley rats receiving an intravenous infusion of S-nitroso-L-cysteine (100 or 200 nmol/kg/min) markedly diminished the ability of intravenous injections of the potent synthetic opioid, fentanyl (10, 25, and 50 μg/kg), to depress the frequency of breathing, tidal volume, and minute ventilation. Our study also found that the ability of intravenously injected fentanyl (10, 25, and 50 μg/kg) to disturb eupneic breathing, which was measured as a marked increase of the non-eupneic breathing index, was substantially reduced in unanesthetized rats receiving intravenous infusions of S-nitroso-L-cysteine (100 or 200 nmol/kg/min). In contrast, the deleterious effects of fentanyl (10, 25, and 50 μg/kg) on frequency of breathing, tidal volume, minute ventilation and non-eupneic breathing index were fully expressed in rats receiving continuous infusions (200 nmol/kg/min) of the parent amino acid, L-cysteine, or the D-isomer, namely, S-nitroso-D-cysteine. In addition, the antinociceptive actions of the above doses of fentanyl as monitored by the tail-flick latency assay, were enhanced by S-nitroso-L-cysteine, but not L-cysteine or S-nitroso-D-cysteine. Taken together, these findings add to existing knowledge that S-nitroso-L-cysteine stereoselectively modulates the detrimental effects of opioids on breathing, and opens the door for mechanistic studies designed to establish whether the pharmacological actions of S-nitroso-L-cysteine involve signaling processes that include 1) the activation of plasma membrane ion channels and receptors, 2) selective intracellular entry of S-nitroso-L-cysteine, and/or 3) S-nitrosylation events. Whether alterations in the bioavailability and bioactivity of endogenous S-nitroso-L-cysteine is a key factor in determining the potency/efficacy of fentanyl on breathing is an intriguing question.

Exposure to hypoxia elicits changes in mean arterial blood pressure (MAP), heart rate, and frequency of breathing (fR). The objective of this study was to determine the role of nitric oxide (NO) in the cardiovascular and ventilatory responses elicited by brief exposures to hypoxia in isoflurane-anesthetized rats. The rats were instrumented to record MAP, heart rate, and fR and then exposed to 90 s episodes of hypoxia (10% O2, 90% N2) before and after injection of vehicle, the NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME), or the inactive enantiomer D-NAME (both at 50 µmol/kg iv). Each episode of hypoxia elicited a decrease in MAP, bidirectional changes in heart rate (initial increase and then a decrease), and an increase in fR. These responses were similar before and after injection of vehicle or D-NAME. In contrast, the hypoxia-induced decreases in MAP were attenuated after administration of L-NAME. The initial increases in heart rate during hypoxia were amplified whereas the subsequent decreases in heart rate were attenuated in L-NAME-treated rats. Finally, the hypoxia-induced increases in fR were virtually identical before and after administration of L-NAME. These findings suggest that NO factors play a vital role in the expression of the cardiovascular but not the ventilatory responses elicited by brief episodes of hypoxia in isoflurane-anesthetized rats. Based on existing evidence that NO factors play a vital role in carotid body and central responses to hypoxia in conscious rats, our findings raise the novel possibility that isoflurane blunts this NO-dependent signaling. [ABSTRACT FROM AUTHOR]

The mechanical inhomogeneity of the respiratory system is frequently investigated by measuring the frequency dependence of dynamic compliance, but no data are currently available describing the effects of body temperature variations. The aim of the present report was to study those effects in vivo. Peak airway pressure was measured during positive pressure ventilation in eight anesthetized rats while breathing frequency (but not tidal volume) was altered. Dynamic compliance was calculated as the tidal volume/peak airway pressure, and measurements were taken in basal conditions (mean rectal temperature 37.3 °C) as well as after total body warming (mean rectal temperature 39.7 °C). Due to parenchymal mechanical inhomogeneity and stress relaxation-linked effects, the normal rat respiratory system exhibited frequency dependence of dynamic lung compliance. Even moderate body temperature increments significantly reduced the decrements in dynamic compliance linked to breathing rate increments. The results were analyzed using Student's and Wilcoxon's tests, which yielded the same results ( p < 0.05). Body temperature variations are known to influence respiratory mechanics. The frequency dependence of dynamic compliance was found, in the experiments described, to be temperature-dependent as temperature variations affected parenchymal mechanical inhomogeneity and stress relaxation. These results suggest that body temperature variations should be taken into consideration when the dynamic compliance-breathing frequency relationship is being examined during clinical assessment of inhomogeneity of lung parenchyma in patients. [ABSTRACT FROM AUTHOR]

The aim of this paper is to present research work into designing prototype textile sensors devoted to measuring a human physiological signal, the frequency of breathing. These sensors may be used in medical applications or for firemen's protective clothing. The aim of our work was to design a textile sensor which could be easily included in clothing structures. The preliminary research into the sensorial materials is described in this paper. [ABSTRACT FROM AUTHOR]

Under conditions of heat stress and hyperosmotic dehydration, both animals and humans reduce thermoregulatory evaporation and regulate deep body temperature at elevated levels. Regarding the mechanisms, the main role in producing these thermoregulatory changes during dehydration is attributed to the increased osmolality of body fluids, although the role of the decreased plasma volume without changes in plasma osmolality (hypovolemia/isosmotic dehydration) has not been so far investigated. There are also controversial experimental results regarding the effects of dehydration on heat stress-induced cutaneous vasodilation. Therefore, this paper studied the effects of hypovolemia/isosmotic dehydration on cardiorespiratory responses to hyperthermia and its physical treatment in 17 anaesthetized adult rabbits. The animals were divided into two groups: normovolemic group (NV; n &ThickSpace;=&ThickSpace;10) and hypovolemic group (HV; n &ThickSpace;=&ThickSpace;7). In the HV group, hypovolemia/isosmotic dehydration (decrease in plasma volume by 16.1&ThickSpace;±&ThickSpace;1.2%) was induced by furosemide (5&ThickSpace;mg&ThickSpace;kg -1 i.v.) without change in measured plasma Na + concentration. Hyperthermia (the rise in body temperature (BT) to 42°C by a gradual body surface heating) caused significant increase in minute ventilation ( V E ) in both groups. However, V E values were significantly higher in the HV rabbits compared to the NV animals despite the lower breathing frequency ( p &ThickSpace; [ABSTRACT FROM AUTHOR]