scholarly journals Blood flow distribution in submerged and surface-swimming ducks

1992 ◽  
Vol 166 (1) ◽  
pp. 285-296
Author(s):  
R. Stephenson ◽  
D. R. Jones
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Water Surface ◽  
Imaging Technique ◽  
Flow Distribution ◽  
Tissue Blood Flow ◽  
Blood Flow Distribution ◽  
Radiological Imaging ◽  
Aythya Americana

Observations that the response of the avian heart rate to submergence varies under different circumstances have led to speculation about variability of blood flow distribution during voluntary dives. We used a radiological imaging technique to examine the patterns of circulating blood flow in captive redhead ducks (Aythya americana) during rest, swimming, escape dives, forced dives and trapped escape dives and have shown that blood flow distribution in escape dives was the same as that in ducks swimming at the water surface. The response during trapped escape dives, however, was highly variable. Blood pressure was unchanged from the resting value during all activities. Predictions made about blood flow distribution during unrestrained dives on the basis of heart rate and other indirect data were confirmed in this study. However, the trapped escape dive responses indicated that heart rate alone is not always a reliable indicator of tissue blood flow in exercising ducks.

Systemic and regional hemodynamic effects of angiotensin-(1–7) in rats

2003 ◽  
Vol 284 (6) ◽  
pp. H1985-H1994 ◽  
Author(s):  
Walkyria O. Sampaio ◽  
Antônio A. S. Nascimento ◽  
Robson A. S. Santos
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Cardiac Index ◽  
Total Peripheral Resistance ◽  
Peripheral Resistance ◽  
Flow Distribution ◽  
High Dose ◽  
Blood Flow Distribution ◽  
Potent Effect

The systemic and regional hemodynamics effects of ANG-(1–7) were examined in urethane-anesthetized rats. The blood flow distribution (kidneys, skin, mesentery, lungs, spleen, brain, muscle, and adrenals), cardiac output, and total peripheral resistance were investigated by using fluorescent microspheres. Blood pressure and heart rate were recorded from the brachial artery. ANG-(1–7) infusion (110 fmol · min−1 · 10 min−1 iv) significantly increased blood flow to the kidney (5.10 ± 1.07 to 8.30 ± 0.97 ml · min−1 · g−1), mesentery (0.73 ± 0.16 to 1.17 ± 0.49 ml · min−1 · g−1), brain (1.32 ± 0.44 to 2.18 ± 0.85 ml · min−1 · g−1), and skin (0.07 ± 0.02 to 0.18 ± 0.07 ml · min−1 · g−1) and the vascular conductance in these organs. ANG-(1–7) also produced a significant increase in cardiac index (30%) and a decrease in total peripheral resistance (2.90 ± 0.55 to 2.15 ± 0.28 mmHg · ml−1 · min · 100 g). Blood flow to the spleen, muscle, lungs, and adrenals, as well as the blood pressure and heart rate, were not altered by the ANG-(1–7) infusion. The selective ANG-(1–7) antagonist A-779 reduced the blood flow in renal, cerebral, mesenteric, and cutaneous beds and blocked the ANG-(1–7)-induced vasodilatation in the kidney, mesentery, and skin, suggesting a significant role of endogenous ANG-(1–7) in these territories. The effects of ANG-(1–7) on the cerebral blood flow, cardiac index, systolic volume, and total peripheral resistance were partially attenuated by A-779. A high dose of ANG-(1–7) (11 pmol · min−1 · 10 min−1) caused an opposite effect of that produced by the low dose. Our results show for the first time that ANG-(1–7) has a previously unsuspected potent effect in the blood flow distribution and systemic hemodynamics.

Regional blood flow distribution during the Cushing response: alterations with adrenergic blockade

1985 ◽  
Vol 248 (1) ◽  
pp. H98-H108
Author(s):  
D. G. van Wylen ◽  
L. G. D'Alecy
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Regional Blood Flow ◽  
Flow Distribution ◽  
Peripheral Tissue ◽  
Systemic Hypertension ◽  
Tissue Blood Flow ◽  
Blood Flow Distribution ◽  
Beta Receptor ◽  
Cushing Response

Regional blood flow distribution (microspheres) and cardiac output (CO, thermal dilution) were measured during the Cushing response in unblocked (UB), beta-receptor-blocked (BB, 2 mg/kg propranolol iv), or alpha-receptor blocked (AB, 0.5 mg/kg + 0.5 mg X kg-1 X min-1 phentolamine iv) chloralose-anesthetized dogs. Intracranial pressure was increased to 150 mmHg by infusion of temperature-controlled artificial cerebrospinal fluid into the cisterna magna. Similar increases in mean arterial pressure were seen in UB and BB, but in AB a Cushing response could not be sustained. In UB, cerebral blood flow (CBF) decreased 50%, coronary blood flow (CoBF) increased 120%, and peripheral tissue blood flow was reduced only in the kidneys (18%) and the intestines (small 22%, large 35%). Blood flow to the other viscera, skin, and skeletal muscle was unchanged. CO (16%) and heart rate (HR, 38%) decreased, and total peripheral resistance (TPR, 68%) and stroke volume (SV, 38%) increased. In BB, CBF decreased 50%, CoBF decreased 20%, and blood flow was reduced 40-80% in all peripheral tissues. CO (69%) and HR (62%) decreased, TPR increased 366%, and SV was unchanged. We conclude that the Cushing response in UB animals combines an alpha-receptor-mediated vasoconstriction with a beta-receptor cardiac stimulation. The beta-mechanism is neither necessary nor sufficient for the hypertension. However, the combination of alpha- and beta-adrenergic mechanisms maintains cardiac output and peripheral tissue blood flow relatively constant while producing a systemic hypertension.

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.

Hemodynamic disturbances in the rat as a function of the number of microspheres injected

1983 ◽  
Vol 245 (6) ◽  
pp. H920-H923 ◽  
Author(s):  
K. A. Stanek ◽  
T. L. Smith ◽  
W. R. Murphy ◽  
T. G. Coleman
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Reference Sample ◽  
Flow Distribution ◽  
Fluid Replacement ◽  
Blood Flow Distribution ◽  
Radioactive Microsphere ◽  
Electromagnetic Flowmetry ◽  
Radioactive Microsphere Technique ◽  
Hemodynamic Disturbance

The purpose of this study was to reevaluate the radioactive microsphere technique used to measure blood flow distribution. The rats were conscious when studied. A dextrose solution with specific gravity of 1.3 was used as the suspension media instead of 10% dextran, which has previously been shown to cause hypotension. The microspheres were injected into the left atrium, which provided for maximal mixing with the blood before being ejected into the aortic arch. Ficoll-70 was given after each reference sample as a fluid replacement. With these modifications an injection of 360,000 microspheres or less caused no hemodynamic disturbances, as judged by electromagnetic flowmetry. After 1.4 X 10(6) microspheres had accumulated in the rat (several injections) the only significant hemodynamic disturbance was a decreased heart rate. This study establishes the limits in the rat regarding the number of microspheres that can be injected before hemodynamic disturbances result.

Cardiovascular and metabolic responses to low dose adrenaline infusion: an invasive study in humans

1986 ◽  
Vol 70 (2) ◽  
pp. 199-206 ◽  
Author(s):  
U. Freyschuss ◽  
P. Hjemdahl ◽  
A. Juhlin-Dannfelt ◽  
B. Linde
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Adipose Tissue ◽  
Cardiac Output ◽  
Cyclic Amp ◽  
Plasma Concentrations ◽  
Metabolic Responses ◽  
Tissue Blood Flow ◽  
Arterial Plasma

1. Cardiovascular and metabolic responses to intravenous infusions of adrenaline (ADR), which raised arterial plasma ADR in a stepwise fashion from 0.3 to 1.3, 2.3 and 6.0 nmol/l, were studied in 11 healthy volunteers. 2. ADR evoked marked and concentration-dependent increases in stroke volume and cardiac output (thermodilution), as well as decreases in the vascular resistances of the systemic circulation, calf and adipose tissue. These changes were significant from 1.3 nmol/l ADR. Less marked effects were found on blood pressure and heart rate. 3. Significant arterial ADR concentration-effect relationships were found for cyclic AMP, glycerol, glucose, lactate and noradrenaline, but not for insulin. Cyclic AMP and glycerol were significantly elevated at 1.3, glucose at 2.3, but lactate not below 6.0 nmol/l ADR. Increases in adipose tissue blood flow and arterial glycerol levels were correlated (P < 0.001), suggesting a metabolic component in the blood flow response of adipose tissue. 4. Invasive haemodynamic measurements revealed that ADR at arterial concentrations within the lower physiological range had considerable effects on cardiac output and vascular resistances, despite moderate changes in the conventional non-invasive haemodynamic variables blood pressure and heart rate. 5. ADR elicited clear-cut responses at arterial plasma concentrations attained during various kinds of mild to moderate stress.

Myocardial flow during tachycardia in dogs with chronic left ventricular hypertrophy

1986 ◽  
Vol 250 (6) ◽  
pp. H968-H973 ◽  
Author(s):  
J. C. Rembert ◽  
J. C. Greenfield
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Left Ventricular Hypertrophy ◽  
Myocardial Blood Flow ◽  
Aortic Coarctation ◽  
Ventricular Hypertrophy ◽  
Flow Distribution ◽  
Left Ventricular ◽  
Blood Flow Distribution ◽  
Myocardial Flow

The effect of pacing-induced tachycardia on transmural myocardial blood flow distribution was studied in 16 awake dogs with left ventricular hypertrophy secondary to modified aortic coarctation banding done at 7-10 wk of age. They were studied between 11 and 50 mo of age. In those dogs with mild and moderate left ventricular hypertrophy, the blood flow distribution was normal during resting conditions and remained normal during an increased heart rate of 250 beats/min. In the six dogs with severe hypertrophy (left ventricle/body wt greater than 7.0 g/kg) a reduced flow to the endocardial layers was present during resting conditions (endocardial/epicardial 0.91 +/- 0.09), but during tachycardia the endocardial-to-epicardial ratio normalized to 1.26 +/- 0.08 (mean +/- SEM). These data indicate that, in dogs with significant left ventricular hypertrophy, the vasoregulator mechanism functions adequately to maintain normal transmural myocardial blood flow distribution during tachycardia. In addition, studies were carried out to compare the magnitude of hypertrophy with the hemodynamic load secondary to coarctation banding.

Hemodynamic Effects And Changes Of Blood Flow Distribution By Dextran 70, Dihydroergotamin (DHE) And Their Combination

1981 ◽  
Author(s):  
B Lindblad ◽  
D Bergqviat
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Femoral Vein ◽  
Venous Pressure ◽  
Flow Distribution ◽  
Tissue Blood Flow ◽  
Blood Flow Distribution ◽  
Arterial Blood ◽  
Dextran 70 ◽  
The Central Nervous System

Dextran 70 and DHE are both effective in reducing the risk for postoperative thromboembolic complications. As they at least in part have different mechanisms of action it is important to analyse if their combination potentiates the prophylactic effect. Therefore it is necessary to study the effect on hemodynamics and tissue blood flow, a problem which is delt with in this report.MATERIAL AND METHODS: In 18 dogs the following parameters were followed: cardiac output, heart rate, arterial blood pressure, central venous pressure, pulmonary artery pressure, left atrium pressure and volume blood flow in the femoral vein. Blood flow distribution was determined by the radioactive microsphere technique.RESULTS: Dextran 70 gave an increase of cardiac output and femoral vein flow. Other hemodynamic parameters were mainly unaffected. Total peripheral resistance decreased. DHE increased arterial blood pressure, central venous pressure and pulmonary arterial pressure. Cardiac output and femoral vein flow were unchanged.Tissue blood flow increased in general slightly after infusion of dextran 70. No significant change in blood flow distribution was seen. DHE reduced pancreatic and thyroid blood flow and increased tissue blood flow to the central nervous system. The blood flow to other organs including the heart was unaffected. The combination of dextran 70 and DHE influenced hemodynamic parameters and flow distribution in an additative way.CONCLUSIONS: From this experimental study it is concluded that it is possible to combine dextran and DHE without inducing a circulatory overload. DHE increased tissue blood flow to the central nervous system.

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