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PubMed1978

The actions of secretagogues on oxygen uptake by isolated mammalian parietal cells.

The action of histamine, carbamylcholine, and gastrin on oxygen uptake by cells isolated from canine fundic mucosa was studied in vitro. Viable mucosal cells were prepared by exposure of separated mucosa sequentially to collagenase and EDTA. Oxygen consumption, determined by polarography, was chosen as an index of physiological response of mucosal cells to secretagogues. Isobutyl methyl xanthine (IMX), carbamylcholine, histamine, and gastrín each independently stimulated oxygen uptake by the unfractionated mucosal cells. The response to histamine was greatly enhanced when IMX was present. In fractions of varying parietal cell content obtained with the Beckman elutriator rotor, basal and stimulated oxygen uptake correlated with the parietal cell content of the fractions. The percentage increases in oxygen uptake in response to histamine, gastrin, carbamylcholine, and IMX were similar in enriched fractions with from 50 to 85% parietal cells and in unenriched starting fractions. The normalized dose-response relations for histamine with an IMX background and for carbamylcholine were also similar in these two fractions.The specificity of these responses was tested by use of an H(2)-histamine receptor antagonist, metiamide, and an anticholinergic agent, atropine. At the doses used, neither metiamide (0.1 mM) nor atropine (10 muM) inhibited basal oxygen uptake. Histamine, studied with an IMX background, was inhibited by metiamide but not by atropine, while carbamylcholine was inhibited by atropine but not by metiamide. Neither metiamide nor atropine inhibited gastrin-stimulated oxygen uptake. These data indicate that in this in vitro system parietal cells account for most of the increase in oxygen uptake produced by exposure to gastric secretagogues and that histamine, gastrin, and carbamylcholine each independently stimulate oxygen uptake by the parietal cell. The specificity displayed by atropine and metiamide in this in vitro system suggests that the parietal cell has specific receptors for each of these secretagogues.

Animals↗
PubMedDate not supplied

Conditioning program for competitive figure skating.

To test the feasibility that traditional interval training methods could be adapted to the needs of competitive figure skaters, an interval skating program was conducted during a 3-month period for a group of skaters at diverse levels of proficiency. The program required only a small portion of the total ice time utilized by the skaters on a daily basis, i.e., 1/2 hr, three times a week. On alternate days, the skaters used the same amount of time in a strength training program. A flexibility-stretching facet was to be done by the skaters on a daily basis. Progress was evaluated by treadmill oxygen consumption determinations and ability to perform a 1/2-mile skate effort. Over the course of the 3-month period, the skaters in the program showed an average increase in oxygen consumption of 9% from 44.73 cc per kg per min to 55.51 cc per kg per min. This was accompanied by an average 10-sec reduction in the timed effort at the 1/2-mile skate. Subjectively, the skaters were less fatigued during their freestyle skating programs and were able to improve consistency at skilled maneuvers in the last minute of their performances. This initial effort to evaluate the efficacy of this type of a training program for competitive figure skating seems to have proven to be beneficial to the skaters. Currently, we are continuing our efforts to expand the program.

Adolescent↗
PubMed1989

Arm exercise testing with myocardial scintigraphy in asymptomatic patients with peripheral vascular disease.

Arm exercise with myocardial scintigraphy and oxygen consumption determinations was performed by 33 men with peripheral vascular disease, 40 to 74 years of age (group 2). None had evidence of coronary disease. Nineteen age-matched male control subjects (group 1) were also tested to determine the normal endurance and oxygen consumption during arm exercise in their age group and to compare the results with those obtained during a standard treadmill performance. The maximal heart rate, systolic blood pressure, pressure rate product, and oxygen consumption were all significantly lower for arm than for leg exercise. However, there was good correlation between all these parameters for both types of exertion. The maximal heart rate, work load and oxygen consumption were greater for group 1 subjects than in patients with peripheral vascular disease despite similar activity status. None of the group 1 subjects had abnormal arm exercise ECGs, while six members of group 2 had ST segment changes. Thallium-201 scintigraphy performed in the latter group demonstrated perfusion defects in 25 patients. After nine to 29 months of follow-up, three patients who had abnormal tests developed angina and one of them required coronary bypass surgery. Arm exercise with myocardial scintigraphy may be an effective method of detecting occult ischemia in patients with peripheral vascular disease. Those with good exercise tolerance and no electrocardiographic changes or 201T1 defects are probably at lower risk for the development of cardiac complications, while those who develop abnormalities at low exercise levels may be candidates for invasive studies.

Adult↗
PubMed1994

The fetal electrocardiogram: ST waveform analysis during labour.

Intrapartum fetal surveillance is still under debate, despite 30 years of clinical experience and numerous clinical trials. Waveform analysis of the fetal electrocardiogram has emerged not as an alternative to cardiotochography but as a support tool to allow more accurate interpretation of intrapartum events. During hypoxia, the healthy fetus is utilizing a series of defense mechanisms. Among these, the increase in sympathetic activity, with an increase in circulating adrenaline, activates the myocardium with an increase in workload (the product of cardiac output, myocardium contractility and blood pressure). If there is an imbalance between myocardial oxygen supply and consumption, determined by the workload, then anaerobic metabolism, with a breakdown of myocardial glycogen stores starts and high T waves emerges. ST depression with negative T waves has recently been observed during hypoxia experiments in experimentally growth retarded guinea pigs whilst their normally grown littermates showed ST elevation. These findings have stimulated the development of a dedicated fetal ECG monitor - STAN - incorporating both standard CTG and ST waveform analysis. The STAN concept has now been taken through the process of recognized validation including several prospective studies and a large randomized trial in Plymouth of 2400 high risk, term deliveries. The T/QRS ratio is only one parameter to be used - equally important is to identify the occurrence of ST depression with biphasic negative T waves and to interrelate the CTG and the ST waveform as outlined in the clinical guidelines (table I). This table contains the clinical experience gained over many years and has formed the basis for the first randomized controlled trial comparing ST waveform + CTG with CTG only. Obviously, when the T/QRS ratio is used as the only component of such a scheme, confusion emerges. The analysis should also contain cases with significant intrapartum hypoxia. Recent findings indicate that only when cord artery pH falls below 7.0 and when there is substantial metabolic acidemia is there a significant risk of intrapartum asphyxia. Metabolic acidemia should be estimated from base deficit in the extracellular fluid and the combination of cord artery and vein data should allow for a more accurate assessment of intrapartum events, including the assessment of the duration of hypoxia. The Plymouth trial has tested the hypothesis that the combination of ST wave form and CTG analysis compared with CTG analysis only would reduce operative interventions for fetal distress without placing the fetus at a risk.(ABSTRACT TRUNCATED AT 400 WORDS)

Electrocardiography↗
PubMed1997

Effect of feeding blends of Fusarium mycotoxin-contaminated grains containing deoxynivalenol and fusaric acid on growth and feed consumption of immature swine.

Experiments were conducted to determine the effect of feeding diets containing combinations of the Fusarium metabolites deoxynivalenol (DON) and fusaric acid (FA) to starter swine. In all experiments, pigs of approximately 8.2 kg initial weight were fed diets containing blends of mycotoxin-contaminated corn, wheat, and barley for 21 d with growth and feed consumption determined weekly. In the first experiment, diets were determined to contain 0 microgram DON/g + 58.9 micrograms FA/g (control), 4.4 micrograms DON/g + 57.1 micrograms FA/g, 6.0 micrograms DON/g + 48.6 micrograms FA/g, and 7.5 micrograms DON/g + 57.4 micrograms FA/g. The feeding of all diets containing DON caused significant linear depressions in growth and feed intake after only 1 wk. Lower concentrations of DON and FA were fed in the second experiment with diets containing 0 microgram DON/g + 16.3 micrograms FA/g (control), .5 microgram DON/g + 14.3 micrograms FA/g, 1.1 micrograms DON/g + 14.1 micrograms FA/g, and 1.9 micrograms DON/g + 13.6 micrograms FA/g. There was a significant linear reduction in feed intake after 1 wk with increasing levels of dietary DON. Weight gains declined significantly only after 3 wk. Increasing amounts of FA combined with relatively constant amounts of DON were fed in the third experiment. By analysis, diets contained .5 micrograms DON/g + 2.9 micrograms FA/g (control), 2.2 micrograms DON/g + 12.2 micrograms FA/g, 2.5 micrograms DON/g + 15.6 micrograms FA/g, and 2.4 micrograms DON/g + 15.9 micrograms FA/g. In the 1st wk, the feeding of increasing amounts of fusaric acid combined with a relatively constant amount of DON caused a significant linear depression in weight gain. We concluded that a toxicological synergism exists between DON and FA when fed to immature swine and that FA concentrations in feeds should be determined whenever DON analysis is conducted.

Aging↗
PubMed1983

Effect of lysine and methionine supplementation of low protein roaster diets fed after six weeks of age.

Three floor rearing experiments were conducted using male broilers to determine the extent to which the protein level of the diet can be reduced by supplementation with the amino acids methionine and lysine. Corn-soybean type diets were used and three protein levels (18, 15, and 12%) were tested. All rations were computer formulated and those containing 15 and 12% protein were supplemented with DL-methionine and L-lysine HCl. Three replicate pens of about 50 males per pen were assigned to each treatment. Experimental diets were fed from 6 to 10 weeks of age in Experiment 1 and 6 to 9 weeks in Experiments 2 and 3. Birds were all group weighed at weekly intervals and feed consumption determined. Results obtained in Experiments 1 and 3 showed that neither body weight nor feed efficiency was reduced by feeding either 15 or 12% protein diets as long as these diets contained the National Research Council (NRC, 1977) recommended level of methionine and lysine. In Experiment 2 the 12% protein level depressed body weight and feed efficiency. Net returns over feed cost were highest with the 15% protein level in all three experiments. These results indicate that the NRC (1977) recommendation of 18% protein for 6- to 9-week-old broilers may be reduced with adequate amino acid supplementation.

Animals↗
PubMed2000

Trace metals in Antarctica related to climate change and increasing human impact.

Metals are natural constituents of the abiotic and biotic components of all ecosystems, and under natural conditions they are cycled within and between the geochemical spheres--the atmosphere, lithosphere, hydrosphere, and biosphere--at quite steady fluxes. In the second half of the twentieth century, the huge increase in energy and mineral consumption determined anthropogenic emissions of several metals exceeding those from natural sources, e.g., volcanoes and windborne soil particles. In the Northern Hemisphere, the biogeochemical cycles of Pb, Cd, Zn, Cu, and other metals were significantly altered, even in Arctic regions. On the contrary, available data on trace metal concentrations in abiotic matrices from continental Antarctica, summarized in this review, suggest that the biogeochemical cycle of Pb is probably the only one that has been significantly altered by anthropogenic emissions in Antarctica and elsewhere in the Southern Hemisphere, especially in the period 1950-1975. Environmental contamination by other metals from anthropogenic sources in Antarctica itself can generally only be detected in snow samples taken within a range of a few kilometers or several hundred meters from scientific stations. Local metal pollution from human activities in Antarctica may compromise studies aimed at assessing the biogeochemical cycle of trace elements and the effects of global climate change. Thus, this review focuses on concentrations of metals in atmospheric particulate, snow, surface soils, and freshwater from the Antarctic continent and surface sediments and seawater from the Southern Ocean, which can plausibly be regarded as global background values of trace elements. These baselines are also necessary in view of the construction of new stations, the expansion of existing facilities to support research, and the growth of tourism and fisheries. Despite difficulties in making comparisons with data from other remote areas of the world, concentrations of trace metals in most samples of atmospheric particulates, snow, ice, soils, and marine sediments from Antarctica can be taken as global background levels. Comparison between the results of trace element surveys in marine waters of the Southern Ocean and in other seas is practically impossible. The upwelling or subduction of water masses, the seasonality in ice cover and in phytoplankton biomass, the low fallout of atmospheric dust, and many other peculiar characteristics of the Southern Ocean make concentrations of trace metals in surface waters quite variable in space and time. The depletion of nutrients in surface waters, which is a regular feature of many marine environments, rarely occurs in the Southern Ocean. Waters in some regions are characterized by very low concentrations of Fe and Mn, whereas in others the content of Cd is relatively high at the beginning of summer and may decrease about one order of magnitude during the phytoplankton bloom. Although in most Antarctic coastal ecosystems the input of metals from geochemical and anthropogenic sources and from long-range transport is negligible, concentrations of Cd in the waters and biota may be higher than in waters and related species of organisms from polluted coastal areas. Like the Southern Ocean, Antarctic lakes have many peculiar characteristics. They are often perennially ice covered and without outlet, and their water, which is gained only from short-term melting of snow and glaciers in summer, is lost mainly by sublimation of surface ice. Several lakes are distinctly stratified: the water under the ice may be cool, rich in oxygen, and among the cleanest and clearest of natural waters, whereas water near the bottom becomes anoxic, tepid, and richer in major and trace elements. Considering the specificity of Antarctic environments, to evaluate the extent and consequences of global changes and increasing human activities in Antarctica itself, research on the biogeochemistry of trace metals and monitoring programs

Animals↗
PubMed1975

Dynamic characteristics of a metabolic reaction of mice with different responses to irradiation.

The course of the reaction of mice placed in a metabolic chamber and afterwards irradiated with an exposure dose of 610 R was studied by assessing total oxygen consumption and the size of its fluctuation. Fluctuation was greater in non-survivors than in survivors in the initial phase of the metabolic reaction only (P is less than 0.05), while the mean oxygen consumption values for the two groups were the same, In the distribution of the individual values there were more non-survivors in the frequency class with a high fluctuation level and, conversely, more survivors in the low level class (P is less than 0.01). Fluctuation during the studied reaction was more variable in survivors, despite its lower level, than in non-survivors. The reciprocal relationship between the size and fluctuation of oxygen consumption, determined for the whole series of experimental mice at given stages of the metabolic reaction, is linear. Attention is drawn to the association between changes measured in the metabolic rate and motor activity and to the possibility that it is determined by the individual's type of nervous activity.

Animals↗
PubMed1992

Estimation of peak oxygen consumption from a sub-maximal half mile walk in obese females.

This study compared peak oxygen consumption estimated from a half mile sub-maximal walk test with oxygen consumption determined from a maximal treadmill test with 96 obese females. A half mile walk was completed as quickly as possible without running. Retests on 71 subjects were completed to determine the reliability of the half mile walk. Hearts rates were obtained for 15 s immediately upon completion of the walks. Stepwise regression to estimate peak VO2 was used with the following variables: walk time (TM), body weight, height, BMI, age, and heart rate (HR). The best equation was peak VO2 (ml/kg/min) = 53.23 - (1.98 x TM) - (0.32 x BMI) - (0.08 x age), r = 0.76, s.e.e. = 2.89 ml/kg/min. The mean difference between determined and estimated peak VO2 in a cross-validation group of subjects who were not included in the validation group was 0.15 ml/kg/min (n.s.), r = 0.77, s.e.e. = 3.01 ml/kg/min, E = 3.09. Reliability for time to complete the half mile walk was r = 0.87 with 0.1 min difference (n.s.). This study indicated the half mile walk to provide an accurate, reliable estimate of peak VO2 which should be useful in the clinical setting.

Adult↗
PubMed1990

Axillary crutch walking: effects of three training programs.

This study compared the effects of three different training programs on physiologic and perceptual responses during axillary crutch walking (ACW) for a distance of 1 km at self-selected speeds in healthy women. Forty subjects completed 18 training sessions in six weeks according to one of the following regimens: (1) 20 minutes of aerobic arm ergometer training at 50% of peak oxygen consumption determined during arm ergometry; (2) isotonic strength and endurance training of the upper extremities with free weights; or (3) axillary crutching at self-selected speeds for 20 minutes on a rectangular indoor course. In comparison with a control group that did not do any systematic training, all three training groups significantly increased their self-selected ACW speeds after training. This also resulted in a significant increase in their heart rates during ambulation. However, no significant changes were observed in oxygen consumption at the faster ACW speeds, suggesting that the training regimens were effective in improving the metabolic efficiency of ACW. Ratings of perceived exertion were significantly lowered for the three training groups even though cardiorespiratory stress was significantly elevated. No significant differences were observed between the three training programs for any of the variables examined. Since heart rate is a reliable indicator of myocardial oxygen uptake, it was recommended that (1) individuals should be screened for cardiovascular problems before axillary crutches are prescribed as a mode of ambulation, and (2) they should be advised to reduce the speed of ambulation because of the high degree of cardiovascular stress associated with this activity.

Adult↗
PubMed1984

Continuous infusion of endotoxin from an osmotic pump in the conscious, unrestrained rat: a unique model of chronic endotoxemia.

Endotoxin (ET) was administered to conscious, unrestrained rats by continuous intravenous infusion from an Alzet osmotic pump. Delivery of ET was delayed 42 h after surgery by inserting a 100-cm coil of PE-60 tubing between pump and jugular vein. Rats were anorectic following onset of ET delivery; therefore control rats were either fed ad libitum or food-deprived (FD) to match the voluntary consumption of ET rats. Blood was collected from carotid catheters and oxygen consumption determined daily. Body weight, colon temperature, and plasma glucose were similar in ET and FD rats, but ET rats exhibited a transient hyperlactacidemia, progressive leukocytosis, and fall in hematocrit which was not seen in FD rats. Food deprivation resulted in a marked drop in plasma insulin which was not seen in ET rats, despite similar food intake and plasma glucose concentration. Oxygen consumption of ET rats was significantly greater than both fed and FD animals on days 1 and 2 of ET infusion, while mean arterial pressure and heart rate were similar to controls. A unique model of endotoxemia is presented which is characterized by a transient hypermetabolic state, and changes in plasma lactate and insulin levels, white cell count, and hematocrit, which cannot be attributed to food deprivation. The results suggest that ET may be important in the pathogenesis of hypermetabolic sepsis.

Animals↗
PubMedDate not supplied

[Evaluation of adaptation of animals to hypoxic hypoxia by the multiple regression method].

White mice were exposed to hypoxic hypoxia during 30 days. In the study a correlation between the altitude ceiling and various physiological parameters (body weight, body temperature variations in response to a cold stress (5 degrees C), hemoglobin content, coefficients of adaptive oxygen consumption determined as the ratio of oxygen consumption at 6000 m to that at sea level (K1) and the ratio of oxygen consumption in hypoxic environment to that in a normoxic atmosphere (K2) was established. The data obtained allow the conclusion that the multiple regression method can be used for measuring objectively the tension of regulatory systems and for discriminating stages of animal adaptation to hypoxic hypoxia.

Adaptation, Physiological↗
PubMed1994

The contrasting effects of dopamine and norepinephrine on systemic and splanchnic oxygen utilization in hyperdynamic sepsis.

OBJECTIVE: To compare the effects of dopamine and norepinephrine on systemic and splanchnic oxygen utilization in patients with hyperdynamic sepsis. DESIGN: A randomized short-term, interventional study. SETTING: An intensive care unit of a university hospital. PATIENTS: Twenty septic patients with a cardiac index greater than 3.2 L-min-1.m-2 and either a mean arterial pressure (MAP) less than 60 mm Hg or a systemic vascular resistance index less than 1200 dyne.s.cm-5.m-2. METHODS AND INTERVENTIONS: Patients were randomized to receive an infusion of either dopamine or norepinephrine titrated to increase the MAP to greater than 75 mm Hg. The hemodynamic profile, oxygen delivery, oxygen consumption (determined by indirect calorimetry), and gastric intramucosal pH (pHi) (determined by gastric tonometry) were determined at baseline and after 3 hours of achieving the target MAP. RESULTS: Dopamine increased the MAP largely by increasing the cardiac index whereas norepinephrine increased the MAP by increasing the systemic vascular resistance index while maintaining the cardiac index. Although oxygen delivery and oxygen consumption increased in both groups of patients, the pHi increased significantly in those patients treated with norepinephrine whereas the pHi decreased significantly in those patients receiving dopamine (P < .001, for corrected 3-hour value). CONCLUSIONS: This study suggests that dopamine may cause an uncompensated increase in splanchnic oxygen requirements in septic patients. Norepinephrine, however, may have a more favorable hemodynamic profile and improve splanchnic tissue oxygen utilization in sepsis.

Adult↗
PubMed1993

Identification of the critical oxygen delivery for anaerobic metabolism in critically ill septic and nonseptic humans.

OBJECTIVES: To determine the critical oxygen delivery threshold for anaerobic metabolism and to compare its value between septic and nonseptic critically ill patients. DESIGN: Cohort analytic study, consecutive sample. SETTING: Two tertiary care medical and surgical intensive care units in university hospitals. PATIENTS: Nine septic and nine nonseptic critically ill humans. A diagnosis of sepsis was established by the presence of sepsis syndrome, positive cultures obtained within 48 hours of study, and autopsy evidence of a source of infection. METHODS AND INTERVENTIONS: The O2 consumption (determined by indirect calorimetry), O2 delivery (calculated from the Fick equation), and concentration of arterial plasma lactate were simultaneously determined at 5- to 20-minute intervals while life support was discontinued. MAIN OUTCOME MEASURES: Critical O2 delivery, critical O2 extraction ratio, and maximal O2 extraction ratio. RESULTS: In all septic and eight nonseptic patients, O2 delivery and O2 consumption displayed a biphasic relationship over the range of O2 delivery studied. There were no differences in critical O2 delivery threshold (3.8 +/- 1.5 vs 4.5 +/- 1.3 mL.min-1 x kg-1; P > .28), critical O2 extraction ratio (0.61 +/- 0.05 vs 0.59 +/- 0.16; P > .64), and maximal O2 extraction ratio (0.74 +/- 0.08 vs 0.80 +/- 0.11; P > .29) between septic and nonseptic patients. These data have greater than 90% power to detect a difference of 2 mL.min-1 x kg-1 in the critical O2 delivery and 0.1 in the critical and maximal O2 extraction ratios between the septic and nonseptic groups. CONCLUSIONS: The critical O2 delivery for anaerobic metabolism was identified from the biphasic relationship between O2 delivery and O2 consumption in individual humans. The critical O2 delivery is considerably lower than previously reported in humans with the use of pooled group data. Sepsis does not alter the critical O2 delivery for anaerobic metabolism or tissue O2 extraction ability. Interventions to increase O2 delivery to supranormal levels in critically ill humans in the hope of increasing O2 consumption may be inappropriate.

Adult↗
PubMed1995

[Study on skin storage at -20 degrees C].

Small pieces of fresh guinea pig or cadaveric skin, 0.3mm in thickness, were soaked in cryoprotective solution for 30 min, then were put into plastic bags and kept in -20 degrees C refrigerator. Before and after 14, 30, 45, 60, 75 days storage, the skin were sent for succinae dehydrogenase assay (modified Hershey's method) and oxygen consumption determination (microelectrolyte method). The average viabilities measured by succinated dehydrogenase and oxygen consumption were nearly 50% after 60 days storage and 30% after 75 days storage in both guinea pig and cadaveric skin. 37 times of autologous skin stored at -20 degrees C for 1-26 days were grafted on the granulation wounds with good results. Skin can be preserved viably at -20 degrees C for 45 days but not longer than 60 days. This method may be helpful for hospital which has no -80 degrees C deep freezer or liquid nitrogen container.

Animals↗
PubMedDate not supplied

[Ecological correlation between consumption of alcoholic beverages and liver cirrhosis mortality in Mexico].

OBJECTIVE: To determine the correlation between alcohol consumption and mortality from liver cirrhosis in Mexico. MATERIAL AND METHODS: Analysis of the ecological correlation between the patterns of alcohol consumption determined by the National Addiction Survey in 1993 and mortality by liver cirrhosis, in the period between 1971-1993, in the eight regions in which the country was divided. To determine level of correlation, the Pearson and Spearman coefficients were calculated. RESULTS: Significant correlations were only found with the prevalence of spirits and pulque drinkers; with beer drinkers the correlation was negative. CONCLUSIONS: The correlation with pulque is interesting, since pulque consumption is considered to be low scale in some rural areas. The negative correlation with beer may indicate that beer drinking is nor a good indicator of alcoholism. Results, though limited to the possibilities of an ecological study, reveal the necessity of effective actions in the regions where spirits and pulque are consumed in excess.

Adolescent↗
PubMed1976

Myocardial function during hypoxia in the presence of different buffers.

Electrically driven rabbit left atria were exposed to 20 min periods of either hypoxia or anoxia in the presence of a bicarbonate-phosphate buffer, a Tris buffer [tris (hydroxymethyl) aminomethane hydrochloride] or combination of both. The bicarbonate-phosphate buffer system was shown to be important for tissue survival during hypoxia or anoxia whereas recovery was diminished in the presence of Tris only. Stimulus threshold and arrhythmias were shown to increase for atria in Tris. Oxygen consumption determinations on both spontaneously beating right atria and quiescent left atria showed no difference between pre- and post-hypoxia or between different buffers. Tris was shown to elicit a positive inotropic effect without an increase in O2 consumption.

Animals↗