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1.
Morten Buhl Jørgensen Jakob Christensen-Dalsgaard 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,180(5):493-502
We studied the directionality of spike rate responses of auditory nerve fibers of the grassfrog, Rana temporaria, to pure tone stimuli. All auditory fibers showed spike rate directionality. The strongest directionality was seen at low
frequencies (200 – 400 Hz), where the spike rate could change by up to nearly 200␣spikes s−1. with sound direction. At higher frequencies the directional spike rate changes were mostly below 100 spikes s−1. In equivalent dB SPL terms (calculated using the fibers' rate-intensity curves) the maximum directionalities were up to
15 dB at low frequencies and below 10 dB at higher frequencies. Two types of directional patterns were observed. At frequencies
below 500 Hz relatively strong responses were evoked by stimuli from the ipsilateral (+90o) and contralateral (−90o) directions while the weakest responses were evoked by stimuli from frontal (0o or +30o) or posterior (−135o) directions. At frequencies above 800 Hz the strongest responses were evoked by stimuli from the ipsilateral direction while
gradually weaker responses were seen as the sound direction shifted towards the contralateral side. At frequencies between
500 and 800 Hz both directional patterns were seen. The directionality was highly intensity dependent. No special adaptations
for localization of conspecific calls were found.
Accepted: 23 November 1996 相似文献
2.
P. J. Fonseca A. V. Popov 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,180(4):417-427
1. Laser vibrometry and acoustic measurements were used to study the biophysics of directional hearing in males and females
of a cicada, in which most of the male tympanum is covered by thick, water filled tissue “pads”. 2. In females, the tympanal
vibrations are very dependent on the direction of sound incidence in the entire frequency range 1–20 kHz, and especially at
the main frequencies of the calling song (3–7 kHz). At frequencies up to 10 kHz, the directionality disappears if the contralateral
tympanum, metathoracic spiracle, and folded membrane are blocked with Vaseline. This suggests some pressure-difference receiver
properties in the ear. 3. In males, the tympanal vibrations depend on the direction of sound incidence only within narrow
frequency bands (around 1.8 kHz and at 6–7 kHz). At frequencies above 10–12 kHz, the directionality appears to be determined
by diffraction, and the ear seems to work as a pressure receiver. The peak in directionality at 6–7 kHz disappears when the
contralateral timbal, but not the tympanum, is covered. Covering the thin ventral abdominal wall causes the peak around 1.8 kHz
to disappear. 4. Most observed tympanal directionalities, except around 1.8 kHz in males, are well predicted from measured
transmissions of sound through the body and measured values of sound amplitude and phase at the ears at various directions
of sound incidence.
Accepted: 18 October 1996 相似文献
3.
S. R. Soffe 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,180(6):711-715
Young Xenopus tadpoles were used to test whether the pattern of discharge in specific sensory neurons can determine the motor response
of a whole animal. Young Xenopus tadpoles show two main rhythmic behaviours: swimming and struggling. Touch-sensitive skin sensory neurons in the spinal cord
of immobilised tadpoles were penetrated singly or in pairs using microelectrodes to allow precise control of their firing
patterns. A single impulse in one Rohon-Beard neuron (= light touch) could sometimes trigger “fictive” swimming. Two to six
impulses at 30–50 Hz (= a light stroke) reliably triggered fictive swimming. Neither stimulus evoked fictive struggling. Twenty-five
or more impulses at 30–50 Hz (= pressure) could evoke a pattern of rhythmic bursts, distinct from swimming and suitable to
drive slower, stronger movements. This pattern showed some or all the characteristics of “fictive” struggling. These results
demonstrate clearly that sensory neurons can determine the pattern of motor output simply by their pattern of discharge. This
provides a simple form of behavioural selection according to stimulus.
Accepted: 28 November 1996 相似文献
4.
Dagmar Vogel Horst Bleckmann 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,180(6):671-681
The surface-feeding fish Aplocheilus lineatus uses its cephalic lateral line to detect water surface waves caused by prey insects. The ability of Aplocheilus to discriminate between surface waves with aid of the lateral line system was tested by go/no-go conditioning. Our results
show that Aplocheilus can distinguish between single-frequency surface wave stimuli with equal velocity or equal acceleration amplitudes which
differ only in frequency. Frequency difference limens were about 15%, i.e. fish distinguished a 20-Hz wave stimulus from a
23-Hz stimulus in 100% of the trials. Aplocheilus can also discriminate between pure sine-wave stimuli and sine waves which show abrupt frequency changes. In contrast, fish
were unable to distinguish amplitude-modulated wave stimuli (carrier frequency 20, 40 and 60 Hz, modulation frequency 10 and
20 Hz) from pure sine waves of the same frequency, even if amplitude modulation depth was 80%.
Accepted: 27 December 1996 相似文献
5.
Alexander V. Galazyuk Albert S. Feng 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,180(4):301-311
Responses of 117 single- or multi-units in the auditory cortex (AC) of bats (Myotis lucifugus) to tone bursts of different stimulus durations (1– 400 ms) were studied over a wide range of stimulus intensities to determine
how stimulus duration is represented in the AC. 36% of AC neurons responded more strongly to short stimulus durations showing
short-pass duration response functions, 31% responded equally to all pulse durations (i.e., all-pass), 18% responded preferentially
to stimuli having longer durations (i.e., long-pass), and 15% responded to a narrow range of stimulus durations (i.e., band-pass).
Neurons showing long-pass and short-pass duration response functions were narrowly distributed within two horizontal slabs
of the cortex, over the rostrocaudal extent of the AC. The effects of stimulus level on duration selectivity were evaluated
for 17 AC neurons. For 65% of these units, an increase in stimulus intensity resulted in a progressive decrease in the best
duration. In light of the unusual intensity-dependent duration responses of AC neurons, we hypothesized that the response
selectivities of AC neurons is different from that in the brainstem. This hypothesis was validated by results of study of
the duration response characteristics of single neurons in the inferior colliculus.
Accepted: 8 November 1996 相似文献
6.
A. K. Tryba H. B. Hartman 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,180(3):215-221
Receptors monitoring muscle force innervate the opener muscle apodeme in the walking legs of the blue crab, Callinectes sapidus. Biocytin backfills reveal 9–15 bipolar neurons with somata as large as 60 μm positioned at the distal end of the apodeme.
Sensory endings insert into the apodeme and are in series with the opener muscle. The axons of these neurons form the opener
apodeme sensory nerve that merges with the most distal branch of the opener motor nerve. Recordings reveal that the receptors
are not spontaneously active nor do they respond to passive muscle stretch. Isometric muscle contraction evoked by stimulating
the opener excitor motor neuron is the adequate stimulus for receptor firing. Most significant is the finding that during
contraction, over a wide range of forces, the firing rate of individual receptors closely parallels the rate of change of
isometric force. The peak instantaneous frequency typically occurs at the force derivative maximum, but not at maximum force
development. Thus, receptors of the opener apodeme sensory nerve more closely monitor changes in isometric force rather than
the total force achieved.
Accepted: 20 September 1996 相似文献
7.
K.-H. Esser B. Lud 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,180(5):513-522
In the lesser spear-nosed bat, Phyllostomus discolor, maternal directive calls are characterized by an individual type of sinusoidal frequency modulation (= SFM) pattern. Beside
modulation frequency, modulation depth, carrier frequency, and number of modulation cycles per call contribute to the mother's
vocal signature. Since juvenile P. discolor learn to adapt their isolation calls to the corresponding call characteristics of the own mother or even to playback of a
computer-stored directive call, if hand-reared in the absence of conspecifics, the bats' auditory system ought to be able
to resolve interindividual differences in communication call structure. However, quantitative psychoacoustic data on the discrimination
of SFM signals in this species are not available. Thus, in the present study, lesser spear-nosed bats were trained in a two-alternative
forced-choice procedure to discriminate between two alternatingly presented SFM sound signals differing in modulation frequency.
Other characteristics of acoustic stimuli were identical and designed to mimick the fundamental of species-specific calls.
By gradually reducing the difference in modulation frequency between both stimuli within the behavioural relevant range until
the animals' performance dropped below the 75%-correct level, a considerable auditory spectro-temporal resolution has been
revealed. Particularly in comparison to the overall interindividual variation of this call parameter (minimal modulation frequency = 49 Hz,
maximum = 100 Hz), the determined average difference limen for modulation frequency of 2.42 ± 0.29 Hz seems substantial and
sufficient for labelling individuals.
Accepted: 30 November 1996 相似文献
8.
H. Adelsberger J. Dudel 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1996,180(1):53-61
Whereas the inhibitory innervation of the deep extensor abdominal muscle in crayfish is mediated by a weakly acting common
inhibitor, the opener muscle exhibits a stronger inhibition. In the present study the most abundant γ-aminobutyric acid-activated
chloride channel on distal fibers of crayfish opener muscle was characterized by measuring the current responses after applying
pulses of γ-aminobutyric acid to outside-out patches. The results were compared to those obtained earlier with the chloride
channel on the deep extensor abdominal muscle of the same species. The double logarithmic plot of the dose-response relationship
had a slope of n
H = 2.2 in contrast to n
H = 5.3 for the channel on the deep extensor abdominal muscle. The rise time of the current response declined to 1 ms at a
γ-aminobutyric acid concentration of 50 mmol · l−1. With lower concentrations the rise time increased to a maximal value of 280 ms. No peak of the rise time at low γ-aminobutyric
acid concentrations, as observed for the channel on the deep extensor abdominal muscle, was obvious. The open and closed times
were similar to those of the channel of the deep extensor abdominal muscle. Different reaction schemes were discussed to describe
the kinetics of the chloride channel of the opener muscle.
Accepted: 12 August 1996 相似文献
9.
Hilde Spielvogel Armando Rodriguez Brigitte Sempore Esperanza Caceres J.-M. Cottet-Emard Laurent Guillon R. Favier 《European journal of applied physiology and occupational physiology》1997,75(5):400-406
The present study was undertaken to determine the haematological and cardiovascular status, at rest and during prolonged
(1 h) submaximal exercise (approximately 70% of peak oxygen uptake) in a group (n = 12) of chronic coca users after chewing approximately 50 g of coca leaves. The results were compared to those obtained
in a group (n = 12) of nonchewers. At rest, coca chewing was accompanied by a significant increase in heart rate [from 60 (SEM 4) TO 76 (SEM 3)
beats · min−1], in haematocrit [from 53.2 (SEM 1.2) to 55.6 (SEM 1.1)%] in haemoglobin concentration, and plasma noradrenaline concentration
[from 2.8 (SEM 0.4) to 5.0 (SEM 0.5) μmol · l−1]. It was calculated that coca chewing for 1 h resulted in a significant decrease in blood [−4.3 (SEM 2.2)%] and plasma [−8.7 (SEM 1.2)%]
volume. During submaximal exercise, coca chewers displayed a significantly higher heart rate and mean arterial blood pressure.
The exercise-induced haemoconcentration was blunted in coca chewers compared to nonchewers. It was concluded that the coca-induced
fluid shift observed at rest in these coca chewers was not cumulative with that of exercise, and that the hypovolaemia induced
by coca chewing at rest compromised circulatory adjustments during exercise.
Accepted: 29 October 1996 相似文献
10.
Temporal selectivity for complex signals by single neurons in the torus semicircularis of Pleurodema thaul (Amphibia: Leptodactylidae) 总被引:2,自引:0,他引:2
Mario Penna Wen-Yu Lin Albert S. Feng 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,180(4):313-328
Responses of auditory neurons in the torus semicircularis (TS) of Pleurodema thaul, a leptodactylid from Chile, to synthetic stimuli having diverse temporal patterns and to digitized advertisement calls of
P. thaul and three sympatric species, were recorded to investigate their temporal response selectivities. The advertisement call of
this species consists of a long sequence of sound pulses (a pulse-amplitude-modulated, or PAM, signal) having a dominant frequency
of about 2000 Hz. Each of the sound pulses contains intra-pulse sinusoidal-amplitude-modulations (SAMs). Synthetic stimuli
consisted of six series in which the following acoustic parameters were systematically modified, one at a time: PAM rate,
pulse duration, number of pulses, and intra-pulse SAM rate. The carrier frequency of these stimuli was set at the characteristic
frequency (CF) of the isolated units (n = 47). Response patterns of TS units to synthetic call variants reveal different degrees of selectivities for each of the
temporal variables, with populations of neurons responding maximally to specific values found in the advertisement call of
this species. These selectivities are mainly shaped by neuronal responsiveness to the overall sound energy of the stimulus
and by the inability of neurons to discharge to short inter-pulse gaps.
Accepted: 30 October 1996 相似文献
11.
Sherri M. Jones Timothy A. Jones Roshni Shukla 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,180(6):631-638
Short-latency vestibular-evoked potentials to pulsed linear acceleration were characterized in the quail. Responses occurred
within 8 ms following the onset of stimuli and were composed of a series of positive and negative peaks. The latencies and
amplitudes of the first four peaks were quantitatively characterized. Mean latencies at 1.0 g ms−1 ranged from 1265 ± 208 μs (P1, N = 18) to 4802 ± 441 μs (N4, N = 13). Amplitudes ranged from 3.72 ± 1.51 μV (P1/N1, N = 18) to 1.49 ± 0.77 μV (P3/N3, N = 16). Latency-intensity (LI) slopes ranged from −38.7 ± 7.3 μs dB−1 (P1, N = 18) to −71.6 ± 21.9 μs dB−1 (N3, N = 15) and amplitude-intensity (AI) slopes ranged from 0.20 ± 0.08 μV dB−1 (P1/N1, N = 18) to 0.07 ± 0.04 μV dB−1 (P3/N3, N = 11). The mean response threshold across all animals was −21.83 ± 3.34 dB re: 1.0 g ms−1 (N = 18). Responses remained after cochlear extirpation showing that they could not depend critically on cochlear activity.
Responses were eliminated by destruction of the vestibular end organs, thus showing that responses depended critically and
specifically on the vestibular system. The results demonstrate that the responses are vestibular and the findings provide
a scientific basis for using vestibular responses to evaluate vestibular function through ontogeny and senescence in the quail.
Accepted: 18 January 1997 相似文献
12.
S. J. Brown R. B. Child S. H. Day A. E. Donnelly 《European journal of applied physiology and occupational physiology》1997,75(4):369-374
Indirect indices of exercise-induced human skeletal muscle damage and connective tissue breakdown were studied following
a single bout of voluntary eccentric muscle contractions. Subjects (six female, two male), mean (SD) age 22 (2) years performed
a bout of 50 maximum voluntary eccentric contractions of the knee extensors of a single leg. The eccentric exercise protocol
induced muscle soreness (P < 0.05 Wilcoxon test), chronic force loss, and a decline in the 20:100 Hz percutaneous electrical myostimulation force ratio
[P < 0.01, repeated measures analysis of variance (ANOVA)]. Serum creatine kinase (CK) and lactate dehydrogenase (LDH) activities
were elevated (P < 0.01, repeated measures ANOVA) following the bout. The mean (SD) CK and LDH levels recorded 3 days post-exercise were 2815
(4144) IU · l–1 and 375 (198) IU · l–1, respectively. Serum alkaline phosphatase activity showed no changes throughout the study, and a non-significant increase
(P = 0.058, repeated measures ANOVA) in pyridinoline was recorded following the bout. Urinary hydroxyproline (HP) and hydroxylysine
(HL) excretion, expressed in terms of creatinine (Cr) concentration, increased after exercise (P < 0.05 and P < 0.01, respectively, repeated measures ANOVA). An increased HP:Cr was recorded 2 days post-exercise and HL:Cr was increased
above baseline on days 2, 5, and 9 post-exercise. This indirect evidence of exercise-induced muscle damage suggests that myofibre
disruption was caused by the eccentric muscle contractions. Elevated urine concentrations of indirect indices of collagen
breakdown following eccentric muscle contractions suggests an increased breakdown of connective tissue, possibly due to a
localised inflammatory response.
Accepted: 9 October 1996 相似文献
13.
V. M. King B. K. Follett 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,180(5):541-551
c-fos induction was investigated as a potential component in the avian photic entrainment pathway and as a possible means of locating
the central pacemaker in birds. In both quail (Coturnix coturnix japonica) and starlings (Sturnus vulgaris) exposure to 1 h of light induced Fos-lir in the visual suprachiasmatic nucleus but not in the medial suprachiasmatic nucleus. However, the degree of c-fos induction in the visual suprachiasmatic nucleus was similar at different circadian times despite the fact that the light
pulses caused differential phase shifts in the locomotor rhythm. For golden hamsters the same experiment resulted in significantly
different levels of Fos-lir in the suprachiasmatic nucleus, as well as different phase shifts. Starlings and hamsters were also entrained to T-cycles that caused a large daily phase shift (T = 21.5 h in starlings, T = 22.67 hours in hamsters), or no daily phase shift (T = free running period). No difference in the induced levels of Fos-lir in the visual suprachiasmatic nucleus region was observed between the two groups of starlings, but in hamsters there were
significantly different levels of Fos-lir in the suprachiasmatic nucleus between the two groups.
Accepted: 15 November 1996 相似文献
14.
Thomas Waßmer Franziska Wollnik 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1997,167(4):270-279
Body temperature (T
b) of seven European hamsters maintained at constant ambient temperature (T
a = 8 °C) and constant photoperiod (LD 8:16) was recorded throughout the hibernating season using intraperitoneal temperature-sensitive
HF transmitters. The animals spent about 30% of the hibernation season in hypothermia and 70% in inter-bout normothermy. Three
types of hypothermia, namely deep hibernation bouts (DHBs), short hibernation bouts (SHBs), and short and shallow hibernation
bouts (SSHBs), were distinguished by differences in bout duration and minimal body temperature (T
m). A gradual development of SSHBs from the diel minimum of T
b during normothermy could be seen in individual hamsters, suggesting a stepwise decrease of the homeostatic setpoint of T
b regulation during the early hibernation season. Entry into hibernation followed a 24-h rhythm occurring at preferred times
of the day in all three types of hypothermia. DHBs and SHBs were initiated approximately 4 h before SSHBs, indicating a general
difference in the physiological initiation of SSHBs on the one hand and DHBs and SHBs on the other. Arousals from SHBs and
SSHBs also followed a 24-h rhythm, whereas spontaneous arousals from DHBs were widely scattered across day and night. Statistical
analyses of bout length and the interval between arousals revealed evidence for a free-running circadian rhythm underlying
the timing of arousals. The results clearly demonstrate that entries into hypothermia are linked to the light/dark-cycle.
However, the role of the circadian system in the timing of arousals from DHBs remains unclear.
Accepted: 11 December 1996 相似文献
15.
John D. Crawford 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,180(5):439-450
The mormyrid fish Pollimyrus adspersus has auditory specializations for sound pressure detection and uses acoustic displays in its natural social behavior. In this
paper it is shown that auditory neurons in the mesencephalon (torus semicircularis) are activated selectively by temporal
features of complex sounds. Single neurons were recorded while presenting sounds to fish underwater. The stimuli were acoustic
click trains, 400 ms in duration, and were synthesized with differing inter-click-intervals (ICIs). The natural sounds of
this species are composed similarly and the range of ICIs synthesized overlapped with the natural range (5–40 ms). One-third
of the neurons studied were strongly selective for a narrow range of ICIs, increasing spike rate by ten fold or more at the
best ICI compared to the minimum response observed. The best ICI for interval selective neurons remained stable when the sound
pressure of the stimulus was changed. Neurons that were selective gave phasic responses to tone bursts, and most had non-monotonic
rate level functions. The origin of interval selectivity is discussed and a time-based computational mechanism is proposed.
Accepted: 20 December 1996 相似文献
16.
B. Jongsareejit R. N. Z. A. Rahman S. Fujiwara T. Imanaka 《Molecular & general genetics : MGG》1997,254(6):635-642
The gltA gene encoding a glutamate synthase (GOGAT) from the hyperthermophilic archaeon Pyrococcus sp. KOD1 was cloned as a 6.6 kb HindIII-BamHI fragment. Sequence analysis indicates that gltA encodes a 481- amino acid protein (53 269 Da). The deduced amino acid sequence of KOD1-GltA includes conserved regions that
are found in the small subunits of bacterial GOGAT: two cysteine clusters, an adenylate-binding consensus sequence and an
FAD-binding consensus sequence. However, no sequences homologous to the large subunit of bacterial GOGAT were found in the
upstream or downstream regions. In order to examine whether GltA alone can act as a functional GOGAT, GltA was overexpressed
in Escherichia coli BL21 (DE3) cells using an expression plasmid. GltA was purified to homogeneity and shown to be functional as a homotetramer
of approximately 205 kDa, which is equivalent to the molecular weight of the native GOGAT from KOD1, thus indicating that
KOD1-GOGAT is the smallest known active GOGAT. GltA is capable of both glutamine-dependent and ammonia-dependent synthesis
of glutamate. Synthesis of glutamate by KOD1-GltA required NADPH, indicating that this enzyme is an NADPH-GOGAT (EC 1.4.1.13).
The optimum pH for both activities was 6.5. However, GltA exhibited different optimum temperatures for activity depending
on the reaction assayed (glutamine-dependent reaction, 80° C; ammonia-dependent reaction, 90° C).
Received: 30 October 1996 / Accepted: 13 January 1997 相似文献
17.
Birgit Ehmer Wulfila Gronenberg 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1997,167(4):287-296
The antennal movements of eight ant species (subfamilies Ponerinae, Myrmicinae, and Formicinae) are examined by high-frequency
videography. They show a wide range of antennal velocities which is generated by antennal muscles composed of particularly
diverse muscle fibers. Fiber diameter, sarcomere length and histochemically assessed myosin ATPase activity suggest that some
thin fibers are fairly slow, while the bulk of antennal muscle fibers show intermediate or fast properties. These morphological
properties correlate with the antennal movement velocities measured for the respective species. Based on their morphology,
the fibers that generate the fast antennal retraction in some trap-jaw ants appear particularly fast and comprise the shortest
sarcomeres yet described (1.1 μm).
Accepted: 2 January 1997 相似文献
18.
Isabelle Sendowski Gustave Savourey Yves Besnard Jacques Bittel 《European journal of applied physiology and occupational physiology》1997,75(6):471-477
To study the physiological responses induced by immersing in cold water various areas of the upper limb, 20 subjects immersed
either the index finger (T1), hand (T2) or forearm and hand (T3) for 30 min in 5°C water followed by a 15-min recovery period.
Skin temperature of the index finger, skin blood flow (Qsk) measured by laser Doppler flowmetry, as well as heart rate (HR) and mean arterial blood pressure (ˉBPa) were all monitored during the test. Cutaneous vascular conductance (CVC) was calculated as Qsk / ˉBPa. Cold induced vasodilatation (CIVD) indices were calculated from index finger skin temperature and CVC time courses. The
results showed that no differences in temperature, CVC or cardiovascular changes were observed between T2 and T3. During T1,
CIVD appeared earlier compared to T2 and T3 [5.90 (SEM 0.32) min in T1 vs 7.95 (SEM 0.86) min in T2 and 9.26 (SEM 0.78) min
in T3, P < 0.01]. The HR was unchanged in T1 whereas it increased significantly at the beginning of T2 and T3 [+13 (SEM 2) beats · min−1 in T2 and +15 (SEM 3) beats · min−1 in T3, P < 0.01] and then decreased at the end of the immersion [−12 (SEM 3) beats · min−1 in T2, and −15 (SEM 3) beats · min−1 in T3, P < 0.01]. Moreover, ˉBPaincreased at the beginning of T1 but was lower than in T2 and T3 [+9.3 (SEM 2.5) mmHg in T1, P < 0.05; +20.6 (SEM 2.6) mmHg and 26.5 (SEM 2.8) mmHg in T2 and T3, respectively, P < 0.01]. The rewarming during recovery was faster and higher in T1 compared to T2 and T3. These results showed that general
and local physiological responses observed during an upper limb cold water test differed according to the area immersed. Index
finger cooling led to earlier and faster CIVD without significant cardiovascular changes, whereas hand or forearm immersion
led to a delayed and slower CIVD with a bradycardia at the end of the test.
Accepted: 26 November 1996 相似文献
19.
Jan Eivind Østnes Claus Bech 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1997,167(4):241-248
The ontogeny of deep-body cold sensitivity was studied in 1 to 12 days old Pekin ducklings Anas platyrhynchos. Deep-body cold sensitivity was determined by means of thermodes implanted in the abdominal cavity. The thermodes were perfused
with cold water for 15-min periods to lower the core temperature. Cooling of the body core elicited increases in metabolic
rate and vasoconstrictions in the legs of all the ducklings. From the changes induced in metabolic rate and core temperature,
deep-body cold sensitivity values of between −5.17 and −6.36 W · kg−1 · °C−1, were estimated. These values, which are in the range of those reported previously for adult Pekin ducks, did not change
with age, and it is concluded that deep-body cold sensitivity is fully developed at hatching. Our next aim was to investigate
whether the autonomic responses elicited by exposure of ducklings to cold ambient conditions could be explained by temperature
changes within the body core. During cold exposure, the increase in metabolic rate was not accompanied by a concomitant decrease
in core temperature. On the contrary, deep-body temperature increased slightly during the initial phase of cold exposure.
The ducklings attained a metabolic rate amounting to 85–90% of their peak metabolic rate before the core temperature fell
below the regulated level measured at thermoneutrality. Thus, despite the findings that Pekin ducklings have a highly-developed
deep-body cold sensitivity, their metabolic cold defence under natural conditions seems to be mediated primarily by peripheral
thermoreceptors.
Accepted: 7 January 1997 相似文献
20.
C. Traeholt 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1997,167(3):177-184
Five water monitor lizards, Varanus salvator salvator, and four clouded monitor lizards, Varanus bengalensis nebulosus, were caught on Tioman island in Malaysia. A radio-thermistor transmitter was implanted into the buccal cavity of each animal,
and they were released into an enclosure measuring 5.5 × 6.5 metres. The lizards were observed for 9 and 8 days, respectively,
before and after the parietal eye was covered with aluminium foil. With uncovered parietal eye, both species showed a clear
diurnal rhythm, being active only during day time. After covering the parietal eye, the mean locomotor activity of five V. s. salvator decreased from 791 to 107 min · day–1 but remained unchanged around 850 min · day–1 for V. b. nebulosus. The mean duration of locomotor activity decreased in V. s. salvator and V. b. nebulosus after the parietal eye was covered, but V. b. nebulosus maintained its locomotor activity by increasing the number of locomotor bouts. The water monitor spent very little time on
thermoregulation. Its body temperature ranged between 26.3 and 28.4 °C, which decreased after the parietal eye was covered.
The clouded monitor thermoregulated around 28.8–36.0 °C, which remained unchanged after the parietal eye was covered. In both
species, there was a strong correlation between body temperature and ambient temperature. Behavioural abnormalities were recorded
among V. s. salvator with covered parietal eye. They were often observed to be active by night and often slept outside a burrow. The circadian
rhythm of V. b. nebulosus appeared unaffected by shielding of its parietal eye. Captivity combined with shielded parietal eye induced agonistic behaviour
in both species.
Accepted: 11 September 1996 相似文献