[Method of serum magnesium determination in rats].
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Animals↗
Biomedical subjects
M Stupfel
Publications and source records attributed to M Stupfel.
Perspectives in chronobiology of air pollution.
In a series of experiments, male and female Sprague Dawley rats, kept in light (L) from 06(00) to 18(00) alternating with darkness (LD 12:12) inhaled different concentrations of carbon monoxide (50-1,700 ppm) at each of two test times, 12 h apart. A decrease in flow of CO2 (VCO2) resulting from CO inhalation was greater in the active dark (D) than resting light (L) span. Experimental hypoxic mortality of male and female mice also shows circadian variations, being greater in the D than in the L span. Moreover, a difference of mortality was observed betwen hypoxic exposures performed at 12(00) (in LD or DL) and hypoxic exposures performed at 00(00) (in LD or DL). Such results await tests of any extent to which they model responses of human beings to air pollution. In human beings any external environmental circadian, circaseptan and circannual variations in air pollution as such may serve to variable extent as socioeconomic synchronizers of innate rhythms with a corresponding frequency, rather than as solely generators of time patterns in any physiopathologic response to air pollution.
Air Pollution↗
Respiratory ultradian rhythms of mean and low frequencies: a comparative physiological approach.
Recent developments in human rhythmic respiratory pathology lead to this review of the literature for ultradian rhythms of middle and low frequencies, that is having periods longer than the usual respiratory rates, whose periods are seconds or fractions of seconds. Ultradian respiratory movements for respiratory periods (5 less than tau less than 50 min) have been reported in many species of small laboratory animals (mice, rats, guinea-pigs, rabbits, quails). Long-period respiratory rates (20 less than tau less than 90 min) have been found in human fetuses and infants. But they are more difficult to detect in human adults, except during sleep where they have been related to REM and NONREM activities. These respiratory rhythms of middle and low frequencies are supposed to result from dissipative energy structures related to surface-volume relationships, with interlocking chemical clocks, and to be relevant to a basic rest-activity cycle.
Adolescent↗
Respiratory activity variations induced in groups of LD 12:12 synchronized Sprague-Dawley rats by a 100 dB white noise emitted at 12-h intervals.
A white noise is emitted during 2 h, either in the middle of the scotoperiod (activity period) or of the photoperiod (rest period), on grouped specific pathogen free (SPF) male Sprague-Dawley rats, LD 12:12 synchronized by light (L = 6 h = 150 lux). Continuous measurements of VCO2, taken as an index of respiratory activity shows: 1. a short increase both after the beginning and the end of the stimulus, with slight time length differences between young and older rats; 2. a slight (2-3%) continued increase during the photoperiod and a high decrease (13%) during the scotoperiod. These VCO2 variations obtained during and after the white noise emission correspond to measurements of activity displacement and observations of behavior performed on a small sample of rats.
Age Factors↗
COHb formation and acute carbon monoxide intoxication in adult male rats and guinea-pigs.
Respiratory exchange recordings and percentage survivals to lethal concentrations show that rats are more sensitive than guinea-pigs to an acute carbon monoxide intoxication. To avoid circadian respiratory an comportmental differences between rats and guinea-pigs experiments were performed on urethane anesthetized and artificially ventilated animals. This procedure demonstrates that, for an inhaled concentration of 0.05% CO, the rates of formation of COHb do not statistically differ in rats and in guinea-pigs, but that a higher (0.01 less than p less than 0.05) COHb saturation is reached in rats (35%) than in guinea-pigs (25%). For a 2.84% CO inhalation, no statistically significant difference is observed in the rate of COHb formation, but cardiac arrest is sooner (p less than 0.001) observed in rats than in guinea-pigs.
Acute Disease↗