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991.
Animals typically respond to stressful stimuli such as handling by increasing core body temperature. However, small birds in cold environments have been found to decrease body temperature (Tb) when handled over longer periods, although there are no data extending beyond the actual handling event in such birds. We therefore measured both the initial Tb decrease during ringing and standardized Tb sampling, and subsequent recovery of Tb after this handling protocol in wild Great Tits Parus major roosting in nestboxes in winter. Birds reduced their Tb by 2.3 °C during c. 4 min of handling. When birds were returned to their nestboxes after handling, Tb decreased by a further 1.9 °C over c. 2 min, reaching a Tb of 34.6 °C before taking 20 min to rewarm to 2.5 °C above their initial Tb. The Tb reduction during handling could be a consequence of increased heat loss rate from disrupted plumage insulation, whereas Tb reduction after handling might reflect reduced heat production. These are important factors to consider when handling small birds in the cold. 相似文献
992.
The action of Mg2+ on the putative xKv1.1 channel in the myelinated axon of Xenopus laevis was analyzed in voltage clamp experiments. The main effect was a shift in positive direction of the open probability curve
(16 mV at 20 mm Mg2+), calculated from measurements of the instantaneous current at Na reversal potential after 50–100 msec steps to different
potentials. The shift was measured at an open probability level of 25% to separate it from shifts of other K channel populations
in the nodal region. The results could be explained in terms of screening effects on fixed charges located on the surface
of the channel protein. Using the Grahame equation the functional charge density was estimated to −0.45 e nm−2. Analyzing this value, together with previously estimated values from other K channels, with reference to the charge of different
extracellular loops of the channel protein, we conclude that the loop between the transmembrane S5 segment and the pore forming
P segment determines the functional charge density of voltage-gated K channels.
Received: 11 December 1997/Revised: 24 April 1998 相似文献
993.
994.
Kjetil Flydal Andreas Hermansen Per S. Enger Eigil Reimers 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2001,187(4):265-269
The audiogram of two yearling male reindeer (Rangifer tarandus tarandus) were determined using a conditioned suppression/avoidance procedure. During testing, the animal was drinking from a metal bowl while pure tone signals were played at random intervals and followed by an electric shock in the bowl. By breaking contact with the bowl at sound signals, the animal avoided the shock. The animals detected sounds at intensities of 60 dB or less from 70 Hz to 38 kHz. The frequency range of best sensitivity was relatively flat from 1 kHz to 16 kHz, with a best sensitivity of 3 dB at 8 kHz. The hearing ability of reindeer is similar to the hearing ability of other ungulates. 相似文献
995.
Satish Chandra Govind Simin Roumina Lars-Åke Brodin Jacek Nowak Saligrama Srinivasiah Ramesh Samir Kanti Saha 《Cardiovascular ultrasound》2006,4(1):1-9
The ninth edition of the congress of the European Association of Echocardiography (EAE) (former working group of Echocardiography) held in Florence has just finished with a great success of participant attendance (2.842) and abstract submissions. Hot topics at EuroEcho 9 were: 1-live 3-dimensional echocardiography and surgical decision making; in pediatric cardiology; in resynchronization therapy 2- stress echocardiography beyond wall motion: from valve diseases to contractility to coronary flow reserve to diastolic function; 3- pulmonary cardiogenic interstitial thickening recognized by ultrasonic lung comets; 4- the "proven clinical inefficacy" of the many technologies sold as breakthrough: color kinesis, tissue characterization, strain rate, tissue Doppler, applied to stress echocardiography. 相似文献