The effect of in vitro exposure to nitrous oxide on rat fetal and maternal methionine synthase activity was investigated. Enzyme solutions were prepared from livers of fetuses and mothers on day 19 of gestation and exposed to air, 50% oxygen or 50% nitrous oxide in oxygen for periods up to 24 h. Normal activity of methionine synthase in the fetus was about 65% of that in the mother. Activity de...

We have investigated the effects of fentanyl, nitrous oxide, or both, on carotid sinus baroreceptor reflexes in cats during basal chloralose anaesthesia. The bilaterally isolated carotid sinuses were perfused at prevailing systemic arterial pressure or at predetermined levels of pump-controlled pulsatile pressures of 50-200 mm Hg in steps of 25 mm Hg. Other major baroreceptor sites were denerva...

The mutagenic potential of halothane, enflurane and isoflurane in combination with nitrous oxide was investigated using the sex-linked recessive lethal assay in the fruit fly Drosophila melanogaster. Male wild-type flies were exposed for 1 h to 1 or 2% volatile anaesthetic with various concentrations of nitrous oxide up to 75%. They were then mated with untreated females of the Basc marker stra...

We reported previously that nitrous oxide induces pre-emptive analgesia that is partially antagonized by naloxone and totally antagonized by halothane. The aims of this study were to determine if halothane and isoflurane are similar in this respect and to examine if volatile anaesthetics antagonize the analgesic effect of exogenous opioids. We found that 75% nitrous oxide prolonged tail-flick l...

This manuscript presents an overview of published work on nitrous oxide in the permanently ice-covered lakes of the McMurdo Dry Valleys, Antarctica. One of these lakes contains the highest concentration of nitrous oxide reported for natural aquatic systems (> 500 000% with respect to the global average mixing ratio in air). Recent data on nitrous oxide from the major lakes in this region of Ant...

The use of N fertilizer in agriculture is a major source of Nitrous Oxide, an important greenhouse gases. Market-based instruments, such as incentives or taxes, may help reduce Nitrous Oxide emission by changing Nitrogen application rate. Using a dynamic programming approach, we found that changing corn price or fertilizer price have effects on both farm profit and Nitrogen application rate. Ho...

We studied the effects of six inhalation anaesthetics at subanaesthetic concentrations of 0.2 MAC on pain threshold and psychomotor function in six healthy volunteers. When compared with 100% oxygen inhalation, nitrous oxide and methyoxyflurane significantly increased pain threshold as measured by a radiant heat algometer, and prolonged the response time to auditory stimuli. In contrast, haloth...

Although analgesic action of xenon has been reported, little is known about the effect of xenon at the spinal cord, which plays a crucial role in nociceptive transmission. We studied the effect of xenon on nociceptive reflex (the slow ventral root potential) and the monosynaptic reflex in neonatal rat spinal cord in vitro in comparison with nitrous oxide. Xenon (30%) and nitrous oxide (30%) wer...

In order to evaluate the value of the inspiratory to end-tidal oxygen concentration difference (Io2-E'o2) as a monitor during general anaesthesia, we studied 40 orthopaedic patients allocated randomly to four groups: anaesthesia with enflurane or isoflurane in nitrous oxide with either spontaneous or controlled ventilation. (Io2-E'o2) followed an asymptotically increasing curve because of decre...

We have compared the analgesic potency of MAC-equivalent concentrations of xenon (10, 20, 30 and 40%) and nitrous oxide (15, 30, 45 and 60%) in humans using a multimodal experimental pain testing and assessment technique. We tested 12 healthy volunteers in a randomized, single-blind, crossover study. The following experimental pain tests were used: nociceptive reflex to repeated stimuli; pain t...