Regional distribution of blood flow during diving in the duck (Anas platyrhynchos)

1979 ◽  
Vol 57 (5) ◽  
pp. 995-1002 ◽  
Author(s):  
David R. Jones ◽  
Robert M. Bryan Jr. ◽  
Nigel H. West ◽  
Raymond H. Lord ◽  
Brenda Clark
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Cardiac Output ◽  
Mean Arterial Blood Pressure ◽  
Total Peripheral Resistance ◽  
Regional Distribution ◽  
Peripheral Resistance ◽  
Tissue Blood Flow ◽  
Arterial Blood ◽  
The Brain

The regional distribution of blood flow, both before and during forced diving, was studied in the duck using radioactively labelled microspheres. Cardiac output fell from 227 ± 30 to 95 ± 16 mL kg−1 min−1 after 20–72 s of submergence and to 59 ± 18 mL kg−1 min−1 after 144–250 s of submergence. Mean arterial blood pressure did not change significantly as total peripheral resistance increased by four times during prolonged diving. Before diving the highest proportion of cardiac output went to the heart (2.6 ± 0.5%, n = 9) and kidneys (2.7 ± 0.5%, n = 9), with the brain receiving less than 1%. The share of cardiac output going to the brain and heart increased spectacularly during prolonged dives to 10.5 ± 3% (n = 5) and 15.9 ± 3.8% (n = 5), respectively, while that to the kidney fell to 0.4 ± 0.26% (n = 3). Since cardiac output declined during diving, tissue blood flow (millilitres per gram per minute) to the heart was unchanged although in the case of the brain it increased 2.35 times after 20–75 s of submergence and 8.5 times after 140–250 s of submergence. Spleen blood flow, the highest of any tissue predive (5.6 ± 1.3 mL g−1 min−1, n = 4), was insignificant during diving while adrenal flow increased markedly, in one animal reaching 7.09 mL g−1 min−1. The present results amplify general conclusions from previous research on regional distribution of blood flow in diving homeotherms, showing that, although both heart and brain receive a significant increase in the proportionate share of cardiac output during diving only the brain receives a significant increase in tissue blood flow, which increases as submergence is prolonged.

Control of Blood Pressure and the Distribution of Blood Flow

1991 ◽  
Vol 7 (S1) ◽  
pp. 79-84 ◽  
Author(s):  
Hans T. Versmold
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Cardiac Output ◽  
Peripheral Resistance ◽  
Systemic Blood Pressure ◽  
Adrenergic Innervation ◽  
Systemic Blood ◽  
Low Cardiac Output ◽  
Neurohumoral Control ◽  
The Brain

Systemic blood pressure (BP) is the product of cardiac output and total peripheral resistance. Cardiac output is controlled by the heart rate, myocardial contractility, preload, and afterload. Vascular resistance (vascular hindrance × viscosity) is under local autoregulation and general neurohumoral control through sympathetic adrenergic innervation and circulating catecholamines. Sympathetic innovation predominates in organs receivingflowin excess of their metabolic demands (skin, splanchnic organs, kidney), while innervation is poor and autoregulation predominates in the brain and heart. The distribution of blood flow depends on the relative resistances of the organ circulations. During stress (hypoxia, low cardiac output), a raise in adrenergic tone and in circulating catecholamines leads to preferential vasoconstriction in highly innervated organs, so that blood flow is directed to the brain and heart. Catecholamines also control the levels of the vasoconstrictors renin, angiotensin II, and vasopressin. These general principles also apply to the neonate.

Effect of sympathetic blockade on diurnal variation of hemodynamic patterns

1989 ◽  
Vol 256 (3) ◽  
pp. R778-R785 ◽  
Author(s):  
M. I. Talan ◽  
B. T. Engel
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Cardiac Output ◽  
Stroke Volume ◽  
Total Peripheral Resistance ◽  
Peripheral Resistance ◽  
Base Line ◽  
Sympathetic Blockade ◽  
Selective Blockade ◽  
Arterial Blood

Heart rate, stroke volume, and intra-arterial blood pressure were monitored continuously in each of four monkeys, 18 consecutive h/day for several weeks. The mean heart rate, stroke volume, cardiac output, systolic and diastolic blood pressure, and total peripheral resistance were calculated for each minute and reduced to hourly means. After base-line data were collected for approximately 20 days, observation was continued for equal periods of time under conditions of alpha-sympathetic blockade, beta-sympathetic blockade, and double sympathetic blockade. This was achieved by intra-arterial infusion of prazosin, atenolol, or a combination of both in concentration sufficient for at least 75% reduction of response to injection of agonists. The results confirmed previous findings of a diurnal pattern characterized by a fall in cardiac output and a rise in total peripheral resistance throughout the night. This pattern was not eliminated by selective blockade, of alpha- or beta-sympathetic receptors or by double sympathetic blockade; in fact, it was exacerbated by sympathetic blockade, indicating that the sympathetic nervous system attenuates these events. Because these findings indicate that blood volume redistribution is probably not the mechanism mediating the observed effects, we have hypothesized that a diurnal loss in plasma volume may mediate the fall in cardiac output and that the rise in total peripheral resistance reflects a homeostatic regulation of arterial pressure.

Carotid baroreceptor control of liver and spleen volume in cats

1991 ◽  
Vol 260 (1) ◽  
pp. H254-H259
Author(s):  
R. Maass-Moreno ◽  
C. F. Rothe
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Cardiac Output ◽  
Arterial Blood Pressure ◽  
Total Peripheral Resistance ◽  
Venous Pressure ◽  
Peripheral Resistance ◽  
Normal Brain ◽  
Spleen Volume ◽  
Arterial Blood

We tested the hypothesis that the blood volumes of the spleen and liver of cats are reflexly controlled by the carotid sinus (CS) baroreceptors. In pentobarbital-anesthetized cats the CS area was isolated and perfused so that intracarotid pressure (Pcs) could be controlled while maintaining a normal brain blood perfusion. The volume changes of the liver and spleen were estimated by measuring their thickness using ultrasonic techniques. Cardiac output, systemic arterial blood pressure (Psa), central venous pressure, central blood volume, total peripheral resistance, and heart rate were also measured. In vagotomized cats, increasing Pcs by 100 mmHg caused a significant reduction in Psa (-67.8%), cardiac output (-26.6%), total peripheral resistance (-49.5%), and heart rate (-15%) and significantly increased spleen volume (9.7%, corresponding to a 2.1 +/- 0.5 mm increase in thickness). The liver volume decreased, but only by 1.6% (0.6 +/- 0.2 mm decrease in thickness), a change opposite that observed in the spleen. The changes in cardiovascular variables and in spleen volume suggest that the animals had functioning reflexes. These results indicate that in pentobarbital-anesthetized cats the carotid baroreceptors affect the volume of the spleen but not the liver and suggest that, although the spleen has an active role in the control of arterial blood pressure in the cat, the liver does not.

Circulatory effects of acute or chronic endotoxemia in rats

1981 ◽  
Vol 59 (2) ◽  
pp. 204-208 ◽  
Author(s):  
R. Keeler ◽  
Anamaria Barrientos ◽  
K. Lee
Keyword(s):  
Escherichia Coli ◽  
Blood Pressure ◽  
Blood Flow ◽  
Cardiac Output ◽  
Gastrointestinal Tract ◽  
Peripheral Resistance ◽  
Circulatory Effects ◽  
Arterial Blood ◽  
Flow Changes ◽  
Fractional Distribution

A study was made of the effects of acute (4 h) or chronic (4 days) infusion of Escherichia coli endotoxin on cardiovascular function in rats. Rats with acute endotoxemia had a reduced cardiac output but maintained their arterial blood pressure. Fractional distribution of the cardiac output was increased to the liver and reduced to the gastrointestinal tract and skin. No changes in fractional distribution to the kidneys, lungs, or heart were observed although absolute blood flow to these areas was reduced.Rats with chronic endotoxemia had a reduced cardiac output and hypotension with no change in peripheral resistance. Other changes resembled those seen in acute endotoxemia apart from a low renal fraction of the cardiac output. Calculation and interpretation of blood flow changes in these animals was difficult because of a large fall in hematocrit and changes in organ weight.

Cardiac Output by the Dye Dilution Technique Under Thiopental Sodium-Oxygen and Ether Anesthesia

1956 ◽  
Vol 186 (1) ◽  
pp. 101-104 ◽  
Author(s):  
Esther M. Greisheimer ◽  
Dorothy W. Ellis ◽  
George Stewart ◽  
Lydia Makarenko ◽  
Nadia Oleksyshyn ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Cardiac Output ◽  
Arterial Blood Pressure ◽  
Total Peripheral Resistance ◽  
Peripheral Resistance ◽  
Stroke Index ◽  
Ether Anesthesia ◽  
Dye Dilution ◽  
Arterial Blood ◽  
Thiopental Sodium

One hundred-twenty determinations of cardiac output by the dye dilution technic utilizing the cuvette oximeter were made on 20 dogs. Of these, 60 were done under thiopental sodium-oxygen analgesia and 60 were done after supplementing with ether. Arterial blood pressure was recorded by strain gauge. Electrocardiograms were taken periodically. Concentrations of thiopental and ether in arterial blood were determined. Cardiac output began to increase under thiopental analgesia and continued to increase when ether was administered. Arterial blood pressure and heart rate decreased slightly when ether was administered. Stroke index increased when ether was administered. Total peripheral resistance decreased markedly under thiopental analgesia, and continued to decrease when ether was administered. When compared with an earlier study in which cyclopropane was used as the supplementing agent, it was found that cyclopropane and ether exert opposite effects on cardiac output and peripheral resistance despite the fact that the effect on arterial blood pressure is similar under the two agents. Increase in cardiac output was found to be parallel with decrease in total peripheral resistance in this study. Amount of dye injected did not influence cardiac output. Under the conditions of this study, cardiac output was in no way dependent on the concentration of thiopental in the blood nor on the amount injected. Level of ether in the blood did not show much effect, if any, on cardiac output. It is probable that the changes observed in this study are comparable with those which obtain clinically when thiopental-oxygen analgesia is supplemented with ether. Systolic blood pressure is not an infallible guide to other cardiovascular functions since it may remain fairly steady while cardiac output and peripheral resistance undergo marked changes under anesthesia.

Contribution of Stenosis Resistance to the Rise in total Peripheral Resistance during Experimental Renal Hypertension in Conscious Dogs

1981 ◽  
Vol 61 (6) ◽  
pp. 663-670 ◽  
Author(s):  
W. P. Anderson ◽  
P. I. Korner ◽  
J. A. Angus ◽  
C. I. Johnston
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Cardiac Output ◽  
Plasma Renin Activity ◽  
Renal Artery ◽  
Total Peripheral Resistance ◽  
Peripheral Resistance ◽  
Plasma Renin ◽  
Vascular Beds ◽  
Renal Vascular

1. Mild, moderate and severe renal artery stenosis was induced in uninephrectomized conscious dogs by inflating a renal artery cuff to lower distal pressure to 60, 40 or 20 mmHg respectively. The renal artery was narrowed progressively over the next 3 days by further inflation of the cuff to relower the distal renal artery pressure to the initial values. 2. Graded progressive stenosis produced graded progressive rises in blood pressure, plasma renin activity and total renal resistance to flow over the 3 day period, followed by a return to control values 24 h after cuff deflation. 3. The rise in total renal resistance to flow was almost entirely due to the stenosis, with only small changes occurring in renal vascular resistance. 4. in moderate and severe stenosis cardiac output did not alter significantly and thus increases in blood pressure were due to increases in total peripheral resistance. in these groups the resistance to blood flow of the stenosis accounted respectively for about 36 and 26% of the rises in total peripheral resistance. Vasoconstriction of the other non-renal vascular beds accounted for the remainder of the increase in total peripheral resistance. 5. in mild stenosis the changes in both cardiac output and total peripheral resistance were variable and not statistically significant. in this group the rise in stenosis resistance was compensated by vasodilatation of the non-renal vascular beds. 6. in all groups rises in plasma renin activity and blood pressure correlated with the haemodynamic severity of the stenosis. 7. Thus the resistance to blood flow of the moderate and severe renal artery stenoses accounted for one-quarter to one-third of the increases in total peripheral resistance. The remainder of the increase in total peripheral resistance was due to vasoconstriction of nonrenal beds.

Cardiac output and its distribution during diving in the rat

1975 ◽  
Vol 228 (3) ◽  
pp. 733-737 ◽  
Author(s):  
YC Lin ◽  
DG Baker
Keyword(s):  
Blood Pressure ◽  
Skeletal Muscle ◽  
Blood Flow ◽  
Cardiac Output ◽  
Peripheral Resistance ◽  
Diving Response ◽  
Fourfold Increase ◽  
Arterial Blood ◽  
Cardiovascular Model ◽  
Blood Flow Reduction

The diving response was produced by submerging the head of the unanesthetized rat for 60 s, while it was confined in a mesh-wired cone. Heart rate and cardiac output decreased by 73% and 74% from the predive values, respectively, indicating insignificant change in stroke volume. Central systemic arterial blood pressure rose by 22% during diving and a fourfold increase in total peripheral resistance was observed. Blood flow to the coronary, cerebral, and bronchial circulations remained unchanged while a 95% reduction in the intestine and the spleen, a 97% reduction in the kidney, and greater than 99% reduction in the tail and skin were observed during diving. The blood flow reduction from predive values ranged from 50% for liver and skeletal muscle to 75% for the adrenals and 65% for the diaphragm. The redistribution of the drastically reduced cardiac output during head immersion in the rat is similar to that reported for diving mammals. It is suggested that the rat may serve as a useful cardiovascular model for further studies of the diving response in mammals.

Nocturnal variations in peripheral blood flow, systemic blood pressure, and heart rate in humans

1991 ◽  
Vol 261 (4) ◽  
pp. H982-H988
Author(s):  
J. H. Sindrup ◽  
J. Kastrup ◽  
H. Christensen ◽  
B. Jorgensen
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Arterial Blood Pressure ◽  
Flow Rate ◽  
Mean Arterial Blood Pressure ◽  
Blood Flow Rate ◽  
Tissue Blood Flow ◽  
Peripheral Blood Flow ◽  
Arterial Blood

Subcutaneous adipose tissue blood flow rate, together with systemic arterial blood pressure and heart rate under ambulatory conditions, was measured in the lower legs of 15 normal human subjects for 12-20 h. The 133Xe-washout technique, portable CdTe(Cl) detectors, and a portable data storage unit were used for measurement of blood flow rates. An automatic portable blood pressure recorder and processor unit was used for measurement of systolic blood pressure, diastolic blood pressure, and heart rate every 15 min. The change from upright to supine position at the beginning of the night period was associated with a 30-40% increase in blood flow rate and a highly significant decrease in mean arterial blood pressure and heart rate (P less than 0.001 for all). Approximately 100 min after the subjects went to sleep an additional blood flow rate increment (mean 56%) and a simultaneous significant decrease in mean arterial blood pressure (P less than 0.001) were observed. The duration of this hyperemic phase was 116 min. A highly significant reduction of the subcutaneous vascular resistance (50%) was demonstrated during the hyperemic blood flow rate phase compared with the surrounding phases (P less than 0.0001). The synchronism of the nocturnal subcutaneous hyperemia and the decrease in systemic mean arterial blood pressure point to a common, possibly central nervous or humoral, eliciting mechanism.

Peripheral Resistance Changes and Blood Pooling After Endotoxin in Eviscerated Dogs

1958 ◽  
Vol 195 (3) ◽  
pp. 631-634 ◽  
Author(s):  
Lerner B. Hinshaw ◽  
Robert P. Gilbert ◽  
Hiroshi Kuida ◽  
Maurice B. Visscher
Keyword(s):  
Blood Pressure ◽  
Arterial Blood Pressure ◽  
Mean Arterial Blood Pressure ◽  
Total Peripheral Resistance ◽  
Peripheral Resistance ◽  
Endotoxin Shock ◽  
E Coli ◽  
Arterial Blood ◽  
Later Phase

Studies were performed on eviscerated dogs maintained with a constant cardiac inflow with and without injections of lethal amounts of E. coli endotoxin. Continuous recordings of mean arterial blood pressure and total venous return permitted determination of changes in total peripheral resistance and extent of vascular pooling. A significant fall in mean arterial blood pressure occurs within 30 minutes after endotoxin in the eviscerated dog with constant cardiac inflow. There is therefore a decrease in total peripheral resistance. There is also a small but significant increase in vascular pooling exceeding that seen without endotoxin but much reduced from that observed in noneviscerated animals given endotoxin. It is concluded that a decrease in vascular tone occurs after endotoxin and that it probably plays a significant role in the later phase of endotoxin shock in the dog.

Cardiac output distribution and regional blood flow during hypocarbia in monkeys

1985 ◽  
Vol 58 (4) ◽  
pp. 1225-1230 ◽  
Author(s):  
S. Gelman ◽  
K. C. Fowler ◽  
S. P. Bishop ◽  
L. R. Smith
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Regional Blood Flow ◽  
Arterial Blood Flow ◽  
Tissue Blood Flow ◽  
Base Line ◽  
Output Distribution ◽  
Arterial Blood ◽  
Cardiac Output Distribution ◽  
The Brain

Cardiac output distribution and regional blood flow were studied during hypocarbia independent of changes in ventilatory parameters. Fifteen cynomolgus monkeys were anesthetized with methohexital sodium (8 mg/kg im) and hyperventilated through an endotracheal tube. Hypocarbia at two levels, 28 +/- 1.8 and 17 +/- 0.6 Torr, was achieved by a stepwise decreasing CO2 flow into the semiclosed system. Regional blood flow was determined with labeled microspheres. At each stage of experiments two sets of microspheres (9 and 15 microns diam) were used simultaneously. The use of two microsphere sizes allowed evaluation of the relationship between total (nutritive and nonnutritive) tissue blood flow, determined with 15-microns spheres, and nutritive blood flow, determined with 9-microns spheres. There was no change in cardiac output or arterial pressure during both degrees of studied hypocarbia. Hypocarbia was accompanied by a decrease in myocardial blood flow determined with 15-microns spheres and preservation of the flow determined with 9-microns spheres. Splenic blood flow was decreased, whereas hepatic arterial blood flow was increased during both levels of hypocarbia. Blood flow through the brain, renal cortex, and gut showed a biphasic response to hypocarbia: during hypocarbia at 28 +/- 1.8 Torr, blood flow determined with 15-microns spheres was unchanged (in the gut) or decreased (in the brain and kidneys), whereas blood flow determined with 9-microns spheres was decreased. During hypocarbia at 17 +/- 0.6 Torr, blood flow determined with 9-microns spheres had a tendency to restore to base-line values.

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