Ammonia production in the isolated working rabbit heart

1961 ◽  
Vol 200 (2) ◽  
pp. 238-242 ◽  
Author(s):  
H. Feinberg ◽  
Sister Mary Alma
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Oxygen Consumption ◽  
Rabbit Heart ◽  
Ringer Solution ◽  
Heart Weight ◽  
Ammonia Production

Ammonia production, oxygen consumption, heart rate and blood pressure were observed in the isolated working rabbit heart perfused with Krebs-Ringer solution and with Krebs-Ringer solution containing dog hemoglobin. Oxygen consumption and an index to cardiac effort (heart rate x blood pressure) were shown to be correlated. There was a lesser correlation between ammonia production and cardiac effort. The ratio, ammonia production/oxygen consumption, when both are expressed as micromoles/minute/ gram of heart weight, averaged 0.064 ± .006. Perfusate pH was altered by alternately exposing the perfusate to 95%O2– 5%CO2 and 90%O2–10%CO2. No effect on the ratio ammonia production/oxygen consumption was noted. l-Epinephrine, 0.1–1.0 µg/ml, was continuously infused and resulted in an increase in cardiac effort, oxygen consumption, ammonia production and the ratio of ammonia production/ oxygen consumption.

Relation of coronary flow to oxygen supply

1960 ◽  
Vol 199 (1) ◽  
pp. 179-182 ◽  
Author(s):  
Abraham Guz ◽  
George S. Kurland ◽  
A. Stone Freedberg
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Oxygen Content ◽  
Coronary Flow ◽  
Constant Pressure ◽  
Rabbit Heart ◽  
Hemoglobin Solution ◽  
Oxygen Capacity ◽  
Locke Solution ◽  
Solution Change

Coronary flow, heart rate, myocardial oxygen consumption and Walton strain gauge tension were determined in the isolated rabbit heart perfused with hemoglobin solutions of varying oxygen content. Perfusion was carried out under constant pressure and with the hemoglobin solution in equilibrium with 3% CO2 and 97% air under atmospheric tension. Oxygen content was varied from 2 to 18 vol. % by diluting hemoglobin with Ringer-Locke solution. Change from a higher to lower oxyhemoglobin concentration resulted in increased coronary flow; the reserve led to decreased flow. Heart rate, myocardial tension and oxygen consumption were constant at oxygen capacity above 2 vol. %.

VARIOUS EFFECTS OF THYROXINE ANALOGUES ON THE HEART AND SERUM CHOLESTEROL IN THE RAT

1960 ◽  
Vol 21 (1) ◽  
pp. 25-32 ◽  
Author(s):  
G. S. BOYD ◽  
M. F. OLIVER
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Serum Cholesterol ◽  
Rate Ratio ◽  
Heart Weight ◽  
Liver Cholesterol ◽  
Response Curves ◽  
Experimental Conditions ◽  
Cholesterol Levels ◽  
Stimulation Of

SUMMARY A series of twelve iodinated thyroxine analogues was studied for thyro-activity in the rat. Each analogue produced antigoitrogenic activity, increased oxygen consumption, heart rate and heart weight, and decreased serum and liver cholesterol levels. A 'serum cholesterol/heart rate ratio' may be computed for these analogues under fixed experimental conditions. While the dose-response curves for different analogues in any of these assays are rarely parallel, it is, nevertheless, clear that under certain experimental conditions some iodothyronines cause a relatively greater depression of cholesterol levels and less stimulation of heart rate than others. Some of the most active in this respect are DT4, DT3, DT2 and T4F.

Consistent substrate utilization despite reduced flow in hearts with maintained work

1983 ◽  
Vol 244 (6) ◽  
pp. H799-H806 ◽  
Author(s):  
K. A. Fox ◽  
H. Nomura ◽  
B. E. Sobel ◽  
S. R. Bergmann
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Myocardial Oxygen Consumption ◽  
Myocardial Metabolism ◽  
Diastolic Pressure ◽  
Rabbit Heart ◽  
Substrate Utilization ◽  
Left Ventricular ◽  
Low Flow ◽  
Heart Preparation

Assessments of myocardial metabolism based on external detection of accumulation of radiolabeled substrates may be influenced, as a result of alterations in flow, by altered substrate delivery as well as altered work (with concomitant changes in metabolic requirements). To determine whether reduced delivery limits substrate utilization under defined conditions of reduced perfusion, an isolated rabbit heart preparation was employed in which flow was reduced but myocardial oxygen consumption (MVo2) and work were kept constant by adjustment of left ventricular end-diastolic pressure and heart rate. Flow was reduced from 1.5 to 0.5 ml . g-1 . min-1, while work was maintained constant in hearts functioning at either low or high levels of MVo2. Consumption of palmitate remained constant (48.8 +/- 11.6 and 68.8 +/- 23.3 nmol . g-1 . min-1), because the proportion of palmitate extracted increased (8.8 +/- 4 to 29.1 +/- 7.2% and 10.3 +/- 3.4 to 21.0 +/- 6.1%). The results indicate that, despite reduction of flow, hearts at constant work loads can extract increasing proportions of delivered substrates such that net utilization remains constant until flow is reduced below the level required to maintain cellular function. They suggest that, under conditions of low flow, impaired extraction of substrates reflects either primarily or secondarily depressed myocardial metabolism rather than simply decreased delivery of substrate.

scholarly journals Effect of short moderate intensity exercise bouts on cardiovascular function and maximal oxygen consumption in sedentary older adults

2020 ◽  
Vol 6 (1) ◽  
pp. e000672 ◽  
Author(s):  
Karani Magutah ◽  
Kihumbu Thairu ◽  
Nilesh Patel
Keyword(s):  
Blood Pressure ◽  
Older Adults ◽  
Heart Rate ◽  
Oxygen Consumption ◽  
Systolic Blood Pressure ◽  
Maximal Oxygen Consumption ◽  
Cardiovascular Function ◽  
Moderate Intensity ◽  
Group Differences ◽  
Moderate Intensity Exercise

AimTo investigate effect of <10 min moderate intensity exercise on cardiovascular function and maximal oxygen consumption (V˙ O2max) among sedentary adults.MethodsWe studied 53 sedentary urbanites aged ≥50 years, randomised into: (1) male (MS) and (2) female (FS) undertaking three short-duration exercise (5–10 min) daily, and (3) male (ML) and (4) female (FL) exercising 30–60 min 3–5 days weekly. Resting systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate and V˙ O2max were measured at baseline and 8 weekly for 24 weeks.ResultsAt baseline, 50% MS, 61.5% ML, 53.8% FS and 53.8% FL had SBP ≥120 mm Hg, and 14.3% MS, 53.8% ML, 23.1% FS and 38.5% FL had DBP ≥80 mm Hg. At 24 weeks, where SBP remained ≥120 mm Hg, values decreased from 147±19.2 to 132.3±9.6 mm Hg (50% of MS), from 144±12.3 to 128±7.0 mm Hg (23.1% of ML), from 143.1±9.6 to 128.0±7.0 mm Hg (53.8% of FS) and from 152.3±23.7 to 129±3.7 mm Hg (30.8% of FL). For DBP ≥80 mm Hg, MS and FS percentages maintained, but values decreased from 101±15.6 to 84.5±0.7 mm Hg (MS) and 99.0±3.6 to 87.7±4.9 mm Hg (FS). In ML and FL, percentage with DBP ≥80 mm Hg dropped to 15.4% (86.1±6.5 to 82.5±3.5 mm Hg) and (91.4±5.3 to 83.5±0.71 mm Hg). V˙ O2max increased from 26.1±4.4 to 32.0±6.2 for MS, from 25.8±5.1 to 28.8±5.4 for ML (group differences p=0.02), from 20.2±1.8 to 22.7±2.0 for FS and from 21.2±1.9 to 24.2±2.7 for FL (groups differences p=0.38).ConclusionAccumulated moderate intensity exercise bouts of <10 min confer similar-to-better cardiovascular and V˙ O2max improvements compared with current recommendations among sedentary adults.

scholarly journals Cortisol, blood pressure, and heart rate responses to food intake were independent of physical fitness levels in women

2015 ◽  
Vol 40 (11) ◽  
pp. 1186-1192 ◽  
Author(s):  
Sisitha U. Jayasinghe ◽  
Susan J. Torres ◽  
Steve F. Fraser ◽  
Anne I. Turner
Keyword(s):  
Physical Activity ◽  
Blood Pressure ◽  
Heart Rate ◽  
Oxygen Consumption ◽  
Food Intake ◽  
Physical Fitness ◽  
Maximal Oxygen Consumption ◽  
Physical Activity Guidelines ◽  
Time Treatment ◽  
Fitness Levels

This research tested the hypothesis that women who had higher levels of physical fitness will have lower hypothalamo–pituitary–adrenal axis (cortisol) and sympatho-adrenal medullary system (blood pressure and heart rate) responses to food intake compared with women who had low levels of physical fitness. Lower fitness (n = 22; maximal oxygen consumption = 27.4 ± 1.0 mL∙kg−1·min−1) and higher fitness (n = 22; maximal oxygen consumption = 41.9 ± 1.6 mL∙kg−1·min−1) women (aged 30–50 years; in the follicular phase of the menstrual cycle) who participated in levels of physical activity that met (lower fitness = 2.7 ± 0.5 h/week) or considerably exceeded (higher fitness = 7.1 ± 1.4 h/week) physical activity guidelines made their own lunch using standardised ingredients at 1200 h. Concentrations of cortisol were measured in blood samples collected every 15 min from 1145–1400 h. Blood pressures and heart rate were also measured every 15 min between 1145 h and 1400 h. The meal consumed by the participants consisted of 20% protein, 61% carbohydrates, and 19% fat. There was a significant overall response to lunch in all of the parameters measured (time effect for all, p < 0.01). The cortisol response to lunch was not significantly different between the groups (time × treatment, p = 0.882). Overall, both groups showed the same pattern of cortisol secretion (treatment p = 0.839). Systolic blood pressure, diastolic blood pressure, mean arterial pressure, or heart rate responses (time × treatment, p = 0.726, 0.898, 0.713, and 0.620, respectively) were also similar between higher and lower fitness women. Results suggest that the physiological response to food intake in women is quite resistant to modification by elevated physical fitness levels.

Physical training and heart rate and blood pressure variability: a 5-yr randomized trial

2004 ◽  
Vol 286 (5) ◽  
pp. H1821-H1826 ◽  
Author(s):  
Arja L. T. Uusitalo ◽  
Tomi Laitinen ◽  
Sari B. Väisänen ◽  
Esko Länsimies ◽  
Rainer Rauramaa
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Oxygen Consumption ◽  
Blood Pressure Variability ◽  
Maximal Oxygen Consumption ◽  
Final Analysis ◽  
Peak Performance ◽  
Autonomic Modulation ◽  
The Mean ◽  
Time Point

We studied the effect of regular physical activity on cardiac and vascular autonomic modulation during a 5-yr controlled randomized training intervention in a representative sample of older Finnish men. Heart rate variability (HRV) and blood pressure variability (BPV) are markers of cardiac and vascular health, reflecting cardiac and vascular autonomic modulation. One hundred and forty randomly selected 53- to 63-yr-old men were randomized into two identical groups: an intervention (EX) group and a reference (CO) group, of which 89 men remained until the final analysis (EX: n = 47; CO: n = 42). The EX group trained for 30–60 min three to five times a week with an intensity of 40–60% of maximal oxygen consumption. The mean weekly energy expenditure of the training program for the 5-yr training period was 3.80 MJ, and 71% of the EX group exceeded the mean. The EX group had a significantly ( P < 0.01) higher oxygen consumption at ventilatory aerobic threshold (V̇o2VT) than the CO group at the 5-yr time point. V̇o2VT had a tendency to increase in the EX group and decrease in the CO group (interaction P < 0.001) from the baseline to the 5-yr time point. Peak performance did not change. Low-frequency power of R-R interval variability decreased in the EX group ( P < 0.01, by 6%) from the baseline to the 5-yr time point. BPV did not change. In conclusion, low-intensity regular exercise training did not prevent HRV from decreasing or change BPV in 5 yr in older Finnish men.

Oxygen Consumption, Heart Rate, Rating of Perceived Exertion, and Systolic Blood Pressure with Water Treadmill Walking

2008 ◽  
Vol 16 (1) ◽  
pp. 14-23 ◽  
Author(s):  
David R. Dolbow ◽  
Richard S. Farley ◽  
Jwa K. Kim ◽  
Jennifer L. Caputo
Keyword(s):  
Blood Pressure ◽  
Older Adults ◽  
Heart Rate ◽  
Oxygen Consumption ◽  
Systolic Blood Pressure ◽  
Perceived Exertion ◽  
Cardiovascular Responses ◽  
Treadmill Walking ◽  
Rating Of Perceived Exertion ◽  
Water Treadmill

The purpose of this study was to examine the cardiovascular responses to water treadmill walking at 2.0 mph (3.2 km/hr), 2.5 mph (4.0 km/hr), and 3.0 mph (4.8 km/hr) in older adults. Responses to water treadmill walking in 92 °F (33 °C) water were compared with responses to land treadmill walking at 70 °F (21 °C) ambient temperature. After an accommodation period, participants performed 5-min bouts of walking at each speed on 2 occasions. Oxygen consumption (VO2), heart rate (HR), systolic blood pressure (SBP), and rating of perceived exertion (RPE) were significantly higher during therapeutic water treadmill walking than during land treadmill walking. Furthermore, VO2, HR, and RPE measures significantly increased with each speed increase during both land and water treadmill walking. SBP significantly increased with each speed during water treadmill walking but not land treadmill walking. Thus, it is imperative to monitor HR and blood pressure for safety during this mode of activity for older adults.

scholarly journals Chemical Characterisation and Antihypertensive Effects of Locular Gel and Serum of Lycopersicum esculentum L. var. “Camone” Tomato in Spontaneously Hypertensive Rats

Molecules ◽  
2020 ◽  
Vol 25 (16) ◽  
pp. 3758 ◽  
Author(s):  
Paola Marcolongo ◽  
Alessandra Gamberucci ◽  
Gabriella Tamasi ◽  
Alessio Pardini ◽  
Claudia Bonechi ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Spontaneously Hypertensive Rats ◽  
Pressure Control ◽  
Heart Weight ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive ◽  
Industrial Processing ◽  
Blood Cytokines

Blood pressure control in hypertensive subjects calls for changes in lifestyle, especially diet. Tomato is widely consumed and rich in healthy components (i.e., carotenoids, vitamins and polyphenols). The aim of this study was to evaluate the chemical composition and antihypertensive effects of locular gel reconstituted in serum of green tomatoes of “Camone” variety. Tomato serum and locular gel were chemically characterised. The antihypertensive effects of the locular gel in serum, pure tomatine, and captopril, administered by oral gavage, were investigated for 4 weeks in male spontaneously hypertensive and normotensive rats. Systolic blood pressure and heart rate were monitored using the tail cuff method. Body and heart weight, serum glucose, triglycerides and inflammatory cytokines, aorta thickness and liver metabolising activity were also assessed. Locular gel and serum showed good tomatine and polyphenols content. Significant reductions in blood pressure and heart rate, as well as in inflammatory blood cytokines and aorta thickness, were observed in spontaneously hypertensive rats treated both with locular gel in serum and captopril. No significant effects were observed in normotensive rats. Green tomatoes locular gel and serum, usually discarded during tomato industrial processing, are rich in bioactive compounds (i.e., chlorogenic acid, caffeic acid and rutin, as well as the glycoalkaloids, α-tomatine and dehydrotomatine) that can lower in vivo blood pressure towards healthier values, as observed in spontaneously hypertensive rats.

Effect of Different Types of Lower-limb Exercise on Blood Pressure in Hypertensive People: A Randomized, Double-blind Controlled Clinical Trial

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Rozita Hedayti ◽  
Salimeh Mahmoodi ◽  
Rasool Bagheri ◽  
Marjan Biglary ◽  
Amir Hoshang Bakhtiary ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Oxygen Consumption ◽  
Diastolic Blood Pressure ◽  
Controlled Clinical Trial ◽  
Maximum Oxygen Consumption ◽  
Exercise Interventions ◽  
Concentric Exercise ◽  
Significant Difference

Objectives: The current study aimed at determining the immediate and long-lasting effects of eccentric and concentric exercises on hypertension in individuals with high blood pressure. Methods: A total of 45 hypertensive volunteers were randomly assigned to three intervention groups as eccentric exercise (n = 15), concentric exercise (n = 15), and control (n = 15) groups. All the volunteers underwent exercise interventions for four weeks, three sessions per week (12 sessions in total) as treadmill walking with +10% gradient (concentric group), -10% gradient (eccentric group), or neutral gradient. Before the intervention, immediately after the first session of the intervention, after the end of the intervention, and 48 hours after the end of the intervention, systolic and diastolic blood pressure, heart rate, and maximum oxygen consumption were measured and compared between the groups. Results: The positive gradient group had higher diastolic blood pressure 48 h after the intervention than the negative and neutral gradient groups (P < 0.05). There was no significant difference in the other study variables between eccentric and concentric exercise groups (P > 0.05). Statistical analysis showed that eccentric exercises immediately reduced systolic and diastolic blood pressure (P < 0.05). Eccentric and constrictive exercises reduced systolic and diastolic blood pressure for the long term (P < 0.05). Exonerative and constrictive exercises improved the heart rate, maximum oxygen consumption, and systolic blood and diastolic blood pressure in the short and long term (P < 0.05). Conclusions: Eccentric and concentric exercises with immediate and long-lasting effects improved systolic and diastolic blood pressure, as well as heart rate and maximum oxygen consumption. No significant difference was found between the two types of exercises in terms of the variables studied.

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