The American journal of physiology
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We present in this communication an algorithm that offers continuous, on-line, real-time analysis of the power spectrum (CORAPS) of systemic arterial pressure (SAP) signals. Based on direct fast Fourier transform of raw SAP signals into power spectral density, it is suitable for the delineation of acute SAP spectral changes over time after physiological or pharmacological perturbations. Thus it is an improvement over most current methods, which only generate the spectra off-line or from intermittent data. ⋯ We demonstrated and quantified vivid sequential alterations in the low-frequency components (< 3 Hz) of the SAP spectrum, which purportedly reflect the influence of vasomotor, baroreceptor, and respiratory activity on SAP during pentobarbital administration or transient hypertension. Three window options incorporated into the algorithm further improved the frequency or temporal resolution and discrimination of the spectral changes during abrupt hypertension or hypotension. Thus our CORAPS algorithm may be useful as an on-line monitor for acute hemodynamic changes.
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The Predictions Table (PT), a tool for determining students' knowledge, is described. The PT is a matrix consisting of a group of variables and a set of time periods. Students enter in the PT their qualitative predictions of the effects of a perturbation on a physiological system. ⋯ Also, students who worked in groups had significantly greater improvement than did control students. Using CIRCSIM also significantly reduces the number of relationship errors that the students make. They made even fewer errors when an instructor was present in the computer classroom while the students used CIRCSIM.
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Intra-abdominal sepsis was induced in rats by implanting into their abdominal cavities fecal-agar pellets impregnated with Escherichia coli and Bacteroides fragilis. Sham-operated rats received sterile pellets. A group of sterile- and septic-implanted rats was treated intraperitoneally with diltiazem (1.2 mg/kg) 8 h after implantations. ⋯ Also, vasopressin-induced increase in hepatocyte cytosolic [Ca2+] in diltiazem-treated septic rats was significantly greater than that observed in untreated septic rats. Both Ca2+ and membrane lipid alterations were attenuated with diltiazem treatment of septic rats. These results suggest that prevention or attenuation of Ca2+ channel-mediated Ca2+ influx restores both Ca2+ homeostasis and membrane lipid alteration.
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Comparative Study
Metabolism and ventilation in acute hypoxia: a comparative analysis in small mammalian species.
O2 consumption (VO2), CO2 production (VCO2), and minute ventilation (VE) have been measured during normoxia and hypoxia (10-20 min in 10% O2) in specimens of 27 species from 6 mammalian orders, ranging in body mass (M) from a few grams to several kilograms. In normoxia, both metabolism and VE scaled close to M3/4, VE/VO2 and VE/VCO2 therefore being independent of M. In hypoxia, VE/metabolism increased in all species (on average greater than 100%), mostly because of a drop in VO2. ⋯ The decrease in metabolism during hypoxia was positively correlated with the resting metabolic rate of the species in a manner very similar to what can be calculated from data of previously studied newborn mammals. Hence hypoxia may decrease metabolic rate by decreasing thermogenesis, with larger effects in smaller animals, whether newborns or adults, because of their higher thermogenic requirements. We conclude that 1) hypoxic hypometabolism is a general characteristic of the mammalian response to hypoxia and cannot be neglected in the interpretation of ventilatory and cardiovascular responses and 2) its magnitude is inversely related to the resting VO2 of the species and therefore could be less prominent or possibly absent in adults of larger species.
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The elementary principles of liquid dynamics are described by the equations of Bernoulli and Poiseuille. Bernoulli's equation deals with nonviscous liquids under steady streamline flow. Pressures in such flows are related to gravity and/or acceleration. ⋯ Flow, up or down, must be induced by some source of energy against the resistance of the circuit. In the case of the circulation, the pumping action of the heart supplies the needed energy gradients. Flow in collapsible tubes, like veins, obeys the same basic laws of liquid dynamics except that transmural pressures near zero or below zero reduce markedly the cross-sectional area of the tube, which increases the viscous resistance to flow.(ABSTRACT TRUNCATED AT 250 WORDS)