Effects of temperature and wind on facial temperature, heart rate, and sensation.

Skin temperature measurements of the face have shown that the cheek cools faster than the nose and the nose faster than the forehead. The cooling effect of wind is maximum at wind speeds between 4.5 and 6.7 m/s. Cold winds produce significant bradycardia, which is, however, much more pronounced during the expiratory phase of respiration. A significant correlation was noted between cooling of face and the reflex bradycardia observed. Similarly, a very significant correlation was noted between drop in skin temperature and subjective evaluation of cold discomfort. Consequently, the drop in skin temperature, reflex bradycardia, and subjective evaluation are parameters which are directly affected by cold wind and can be used as adequate indicators of the degree of discomfort. When comparing the present results with the windchill index, it was found that in the zone described as "dangerously cold" the index fits well with the physiological measurements. In the zone described as "bitterly cold," the index by comparison with actual skin temperature measurements and subjective evaluation underestimates the cooling effects of combined temperature and wind by approximately 10 degrees C.     

Effects of wire-bottom caging on heart rate, activity and body temperature in telemetry-implanted rats

Some experimental procedures are associated with placement of animals in wire-bottom cages. The goal of this study was to evaluate stress-related physiological parameters (heart rate [HR], body temperature [BT], locomotor activity [LA], body weight [BW] and food consumption) in rats under two housing conditions, namely in wire-bottom cages and in bedding-bottom cages. Telemetry devices were surgically implanted in male Sprague-Dawley rats. HR, BT and LA were recorded at 5 min intervals. Analysis under each housing condition was performed from 16:00 to 08:00 h of the following day (4 h light, 12 h dark). During almost all of the light phase, the HR of rats housed in wire-bottom cages remained high (371 ± 35 bpm; mean ± SD; n = 6) and was significantly different from that of rats housed in bedding-bottom cages (340 ± 29 bpm; n = 6; P < 0.001; Student's t-test). In general, BT was similar under the two housing conditions. However, when rats were in wire-bottom cages, BT tended to fluctuate more widely during the dark phase. LA decreased when animals were housed in wire-bottom cages, in particular during the dark phase. Moreover, there was a significant difference with respect to the gain in BW: BW of rats housed in bedding-bottom cages increased 12 ± 2 g, whereas that of rats in wire-bottom cages decreased by 2 ± 3 g (P < 0.001). Our results demonstrate that housing rats in wire-bottom cages overnight leads to immediate alterations of HR, BW and LA, which might be related to a stress response.     

Effects of deuterium oxide and temperature on heart rate in Drosophila melanogaster

A non-intrusive optical technique has been developed to monitor heartbeat in late third-instar Drosophila larvae. Heartbeat in this insect is an oscillation that is not temperature compensated. Deuterium oxide lengthens the period of a number of high and low frequency oscillators and clocks in a variety of organisms. To determine whether deuterium affects heart rate, flies were raised on proteated and deuterated media and their heartbeat was monitored at four temperatures ranging from 18 to 33 degrees C. The rate of heartbeat increased linearly with increasing temperature, and decreased with increasing concentrations of deuterium. There was a significant interaction between temperature and deuterium: the higher the concentration of deuterium oxide the less temperature-sensitive was the heart rate. Raising temperatures also increased the amount of "noise" in the rhythm: signal-to-noise ratio, which characterizes the amount of power in a rhythmic signal, decreased with increasing temperatures. Deuterium oxide had no effect on signal-to-noise ratio.     

Effects of season and temperature acclimation on electrocardiogram and heart rate of toads

Electrocardiogram (ECG) was recorded from unrestrained toads of two species, one resistant (Bufo viridis) and the other sensitive (B. regularis) to low temperatures. Although the temperature-sensitive species could not survive at temperatures below 7-8 degrees C, heart rate is linearly and similarly related to ambient temperature in the two species. In B. viridis, the cold resistant species, heart rate in winter was 25% lower than in summer, and the dependency of heart rate on temperature was reduced by 50% in toads acclimated to 10 degrees C in winter. It was not possible to disclose any effect of acclimation on heart rate in summer, due to the large variation in the recorded values. The QRS amplitude in the ECG was considerably reduced at low temperature only in B. viridis. It is concluded that differences in cardiac activity cannot account for the distinct difference in thermal relations of the two species, and that it should reside at other regulatory levels.     

Effects of VDT tasks with a bright display at night on melatonin, core temperature, heart rate, and sleepiness.

The effects of performing video display terminal (VDT) tasks with a bright display (BD) at night on nocturnal salivary melatonin concentration, rectal temperature, heart rate, and sleepiness were examined. Seven healthy male adults performed exciting VDT tasks with a BD and a dark display (DD) and boring VDT tasks with a BD and a DD from 2300 to 0200. The light intensities of the BD and DD were 45 and 15 lx at each subject's eye level, respectively. The exciting VDT task with both BD and DD significantly suppressed the nocturnal decrease in rectal temperature and heart rate and the nocturnal increase in sleepiness. The BD significantly suppressed the nocturnal decrease in rectal temperature during both exciting and boring VDT tasks. The nocturnal salivary melatonin concentration was significantly suppressed by the combination of the exciting task and BD. The results suggest that performing an exciting VDT task with a BD suppresses the nocturnal changes in melatonin concentration and other physiological indicators of human biological clocks.     

Diurnal heart rate and body temperature in marmosets

Marmosets, Saguinus oedipus oedipus and S. fuscicollis, have been shown to have a diurnal heart rate pattern that has a marked difference between high and low values (about 55 beats/minute) and shows a low point during daylight hours around 1300–1400 hours. A similar pattern for body temperature was seen. A species difference existed; the larger S. o. oedipus has a higher heart rate during both light and dark periods. All measurements were made on undisturbed animals at hourly intervals using radiotelemetry. They were kept in a controlled environment with a light cycle of 12L: 12D and a temperature of 27 ± 1°C.     

Effects of three-hour restricted food access during the light period on circadian rhythms of temperature, locomotor activity, and heart rate in rats

The effects of food on biological rhythms may influence the findings of chronopharmacological studies. The present study evaluated the influence of a restricted food access during the rest (light) span of nocturnally active Wistar rats on the 24 h time organization of biological functions in terms of the circadian rhythms of temperature (T), heart rate (HR), and locomotor activity (LA) in preparation for subsequent studies aimed at evaluating the influence of timed food access on the pharmacokinetics and pharmacodynamics of medications. Ten-wk-old male Wistar rats were housed under controlled 12:12 h light:dark (LD) environmental conditions. Food and water were available ad libitum, excepted during a 3 wk period of restriction. Radiotelemetry transmitters were implanted to record daily rhythms in T, HR, and LA. The study lasted 7 wk and began after a 21-d recovery span following surgery. Control baseline data were collected during the first wk (W1). The second span of 3 wk duration (W2 to W4) consisted of the restricted feeding regimen (only 3 h access to food between 11:00 and 14:00 h daily) during the L (rest span) under 12:12 h LD conditions. The third period of 3 wk duration (W5 to W7) consisted of the recovery span with ad libitium normal feeding. Weight loss in the amount of 5% of baseline was observed during W1 with stabilization of body weight thereafter during the remaining 2 wk of food restriction. The 3 h restricted food access during the L rest span induced a partial loss of circadian rhythmicity and the emergence of 12 h rhythms in T, HR, and LA. Return to ad libitum feeding conditions restored circadian rhythmicity in the manner evidenced during the baseline control span. Moreover, the MESORS and amplitudes of the T, HR, and LA 24 h patterns were significantly attenuated during food restriction (p < 0.001) and then returned to initial values during recovery. These changes may be interpreted as a masking effect, since T, HR, and LA are known to directly react to food intake. The consequences of such findings on the methods used to conduct chronokinetic studies, such as the fasting of animals the day before testing, are important since they may alter the temporal structure of the organism receiving the drug and thereby compromise findings.     

The effect of harp music on heart rate, mean blood pressure, respiratory rate, and body temperature in the African green monkey

BACKGROUND: The effectiveness of recorded harp music as a tool for relaxation for non-human primates is explored in this study. METHODS: Konigsberg Instruments Model T27F-1B cardiovascular telemetry devices were implanted into nine African green monkeys (Chlorocebus aethiops). After post-surgical recovery, animals were exposed to recorded harp music. Telemetry data were collected on heart rate, mean blood pressure, respiratory rate, and body temperature for a 30-minute baseline period before music exposure; a 90-minute period of music exposure; and a 90-minute post-exposure period, where no music was played. RESULTS: No statistical differences were noted in heart rate, mean blood pressure, respiratory rate, and body temperature between pre-exposure, exposure, and post-exposure periods. CONCLUSIONS: The lack of response in these African green monkeys may be attributable to their generally calm demeanor in captivity; experiments with a more excitable species such as the rhesus macaque might demonstrate a significant relaxation response to music.     

The daily rhythm of body temperature, heart and respiratory rate in newborn dogs

We asked whether, during the postnatal period, the daily patterns of body temperature (Tb), heart rate (HR) and breathing frequency (f) begin and develop in synchrony. To this end, measurements of HR, f and Tb were performed weekly, on two consecutive days, for the first two postnatal months on puppies of three breeds of dogs (Rottweiler, Cocker Spaniel and Carlino dogs) with very different birth weights and postnatal growth patterns. Ambient conditions and feeding habits were constant for all puppies. The results indicated that (1) the 24-h average Tb increased and average HR and f decreased with growth, (2) the daily rhythms in Tb were apparent by 4 weeks, irrespective of the puppy’s growth pattern, (3) the daily rhythm of Tb in the puppy was not necessarily following that of the mother; in fact, it could anticipate it. (4) The daily rhythms in HR and f were not apparent for the whole study period. We conclude that in neonatal dogs the onset of the daily rhythms of Tb has no obvious relationship with body size or rate of growth and is not cued by the maternal Tb rhythm. The daily rhythms of HR and f do not appear before 2 months of age. Hence, they are not in synchrony with those of Tb.     

Effect of temperature on heart rate in diploid and triploid brook charr, Salvelinus fontinalis, embryos and larvae

Increased cell size in triploid fish likely affects rates of respiratory gas exchange. Respiratory deficiencies can be addressed in fish by adjustments in cardiac output, through changes in heart rate and stroke volume. The aim of this study was to determine whether heart rate differs between triploid and control (diploid) brook charr, Salvelinus fontinalis, at embryo-larval stages, when the heart is easily visible and the fish are relatively inactive. Heart rate was measured at 6, 9 and 12 degrees C at three developmental stages: eyed-egg, hatch and yolk absorption. Heart rate was unaffected by ploidy, but increased with temperature and age from a low of 43.4+/-2.2 beats/min (6 degrees C, eyed egg) to a high of 73.3+/-1.5 beats/min (12 degrees C, yolk absorption). The Q(10) for heart rate was unaffected by ploidy and age, but decreased with temperature from 1.99+/-0.28 at 6-9 degrees C to 1.72+/-0.17 at 9-12 degrees C. Triploid brook charr thus do not use adjustments in heart rate as a mechanism to deal with the physiological consequences of altered haematology at embryo-larval stages.     

Body temperature,oxygen consumption,evaporative water loss and heart rate in the fennec

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• 1.1. Fennecs show marked diurnal variations of body temperature and heart rate.
• 2.2. Basal metabolic rate (0.358 ml/ghr) is 39% lower than predicted by body mass, minimal conductance is reduced for 23%.
• 3.3. Fennecs have a wide thermoneutral zone (23.4–32.0°C) and a low rate of evaporative water loss.
• 4.4. Basal heart rate is considerably reduced. Oxygen pulse increases with decreasing ambient temperature. The higher oxygen demands below thermal neutrality, however, are met primarily by a rise in heart rate.
• 5.5. Newborn fennecs show a metabolic response to cold from the first day of life.

     

Effects of laughing and weeping on mood and heart rate variability

We investigated the effects of laughing and weeping induced by watching comedy and tragedy videos on mood and autonomic nervous function. Ten healthy female subjects volunteered for the experiment. Chest electrocardiogram and respiration curve were recorded before, after, and during watching a comedy or a tragedy video. We also asked them to fill out profiles of mood states (POMS) to evaluate their mood states while watching videos. Autonomic nervous function was estimated by spectral analysis of heart rate variability (HRV). All subjects more or less laughed and wept while watching comedy and tragedy videos, respectively. Anger-hostility score of the POMS decreased and vigor score increased significantly after watching comedy videos, while depression-dejection score increased significantly after watching tragedy ones. Although both contents tended to increase a low to high frequency component ratio (LF/HF ratio) of HRV, the time course of responses was different. The LF/HF ratio which reflects cardiac sympathovagal balance increased immediately after they started watching comedy videos, and returned to the basal level right after they stopped watching, whereas the LF/HF ratio increased gradually to a lesser extent while watching tragedy videos. In contrast, the high-frequency component which reflects cardiac parasympathetic nerve activity gradually decreased while watching both videos but did not return to the basal level after watching tragedy ones. These results suggest that laughing has strong but transient effects on the autonomic nervous system, while weeping or feeling sad has moderate but sustained effects on it.