Vascular resistance and arterial pressure in autoperfused dog hind limb

1962 ◽  
Vol 203 (4) ◽  
pp. 615-620 ◽  
Author(s):  
Kenneth M. Hanson ◽  
Paul C. Johnson
Keyword(s):  
Carbon Dioxide ◽  
Blood Flow ◽  
Arterial Pressure ◽  
Vascular Resistance ◽  
Hind Limb ◽  
Venous Blood ◽  
Significant Rise ◽  
Tissue Pressure ◽  
Hind Limbs ◽  
Polyethylene Tubing

Arterial and venous vascular resistance was studied in 30 isolated dog hind limbs. The preparations were autoperfused from the contralateral femoral artery through a short piece of polyethylene tubing. By application of the isogravimetric technique of Pappenheimer and Soto-Rivera the capillary pressure was determined and the arterial and venous resistances were separately calculated. As arterial pressure in the limbs was progressively reduced from approximately 100 mm Hg down to 20 mm Hg the arterial resistance decreased in 25 of the 30 experiments. The reduction in resistance was particularly evident at arterial pressures below 50 mm Hg. The venous resistance remained relatively constant as the arterial pressure was reduced; a significant rise was seen in only three experiments. Arterial and venous blood oxygen and carbon dioxide contents were determined at various levels of blood flow in ten of the experiments. In general, as the blood flow was decreased, venous oxygen content decreased and carbon dioxide content increased, while oxygen consumption fell. It is concluded that autoregulation of blood flow in the hind limb may, in part, be due to tissue hypoxia. It cannot be explained by the tissue pressure hypothesis.

Increased vascular resistance in paralyzed legs after spinal cord injury is reversible by training

2002 ◽  
Vol 93 (6) ◽  
pp. 1966-1972 ◽  
Author(s):  
Maria T. E. Hopman ◽  
Jan T. Groothuis ◽  
Marcel Flendrie ◽  
Karin H. L. Gerrits ◽  
Sibrand Houtman
Keyword(s):  
Blood Pressure ◽  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Blood Flow ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Vascular Resistance ◽  
Arterial Blood Flow ◽  
Arterial Blood ◽  
Cord Injury

The purpose of the present study was to determine the effect of a spinal cord injury (SCI) on resting vascular resistance in paralyzed legs in humans. To accomplish this goal, we measured blood pressure and resting flow above and below the lesion (by using venous occlusion plethysmography) in 11 patients with SCI and in 10 healthy controls (C). Relative vascular resistance was calculated as mean arterial pressure in millimeters of mercury divided by the arterial blood flow in milliliters per minute per 100 milliliters of tissue. Arterial blood flow in the sympathetically deprived and paralyzed legs of SCI was significantly lower than leg blood flow in C. Because mean arterial pressure showed no differences between both groups, leg vascular resistance in SCI was significantly higher than in C. Within the SCI group, arterial blood flow was significantly higher and vascular resistance significantly lower in the arms than in the legs. To distinguish between the effect of loss of central neural control vs. deconditioning, a group of nine SCI patients was trained for 6 wk and showed a 30% increase in leg blood flow with unchanged blood pressure levels, indicating a marked reduction in vascular resistance. In conclusion, vascular resistance is increased in the paralyzed legs of individuals with SCI and is reversible by training.

Regional blood volume distribution during positive and negative airway pressure breathing in supine humans

1993 ◽  
Vol 75 (4) ◽  
pp. 1740-1747 ◽  
Author(s):  
J. Peters ◽  
B. Hecker ◽  
D. Neuser ◽  
W. Schaden
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Arterial Pressure ◽  
Vascular Resistance ◽  
Airway Pressure ◽  
Left Ventricular ◽  
Whole Body ◽  
Blood Content ◽  
Calf Blood Flow ◽  
Negative Airway Pressure

To assess the effects of continuous positive (CPAP) or negative airway pressure (CNAP) breathing (+/- 10#x2013;12 cmH2O, duration 25 min) on blood content in the body's capacitance vasculature, regional distribution of labeled red blood cells was evaluated in seven spontaneously breathing supine volunteers. Counts were acquired by whole body scans and detectors overlying the liver, intestine, left ventricle, and lower arm, and arterial pressure, heart rate, calf blood flow and vascular resistance, hematocrit, vasopressin, and atrial natriuretic peptide plasma concentrations were also obtained. With CPAP, thoracic, cardiac, and left ventricular counts diminished significantly by 7#x2013;10%, were accompanied by significant increases in counts over both the gut and liver, and remained decreased during CPAP but reversed to baseline with zero airway pressure. Calf blood flow and vascular resistance significantly decreased and increased, respectively, whereas limb counts, arterial pressure, heart rate, and hormone concentrations remained unchanged. With CNAP, in contrast, regional counts and other variables did not change. Thus, moderate levels of CPAP deplete the intrathoracic vascular bed and heart, shifting blood toward the gut and liver but not toward the limbs. No short-term compensation increasing cardiac filling during CPAP was seen. In contrast, CNAP did not alter intrathoracic or organ blood content and, therefore, does not simply mirror the effects evoked by CPAP.

Mesenteric Blood Flow as Influenced by Progressive Hypercapnia

1956 ◽  
Vol 184 (2) ◽  
pp. 275-281 ◽  
Author(s):  
Eugene W. Brickner ◽  
E. Grant Dowds ◽  
Bruce Willitts ◽  
Ewald E. Selkurt
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Arterial Pressure ◽  
Oxygen Content ◽  
Vascular Resistance ◽  
Pulse Pressure ◽  
Venous Pressure ◽  
Mesenteric Blood Flow ◽  
Initial Tendency ◽  
Elevated Heart Rate

The influence of hypercapnia on mesenteric blood flow was studied in dogs subjected to progressive increments in CO2 content of inspired air produced by rebreathing from a large spirometer. Oxygen content was maintained above 21 volumes %. Although some animals showed an initial tendency for mesenteric blood flow to decrease and arterial pressure to increase in the range 0–5 volumes % of CO2, the usual hemodynamic change in the range 5–16 volumes % was an increase in mesenteric blood flow resulting from decrease in intestinal vascular resistance, accompanied by a decline in arterial pressure. Portal venous pressure was progressively elevated. Heart rate slowed in association with an increase in pulse pressure. The observations suggest that in higher ranges of hypercapnia, CO2 has a direct dilating action on the mesenteric vasculature.

Effects of Intraabdominanlly Insufflated Carbon Dioxide and Elevated Intraabdominal Pressure on Splanchnic Circulation 

1998 ◽  
Vol 89 (2) ◽  
pp. 475-482 ◽  
Author(s):  
Manfred Blobner ◽  
Ralph Bogdanski ◽  
Eberhard Kochs ◽  
Julia Henke ◽  
Alexander Findeis ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Blood Flow ◽  
Vascular Resistance ◽  
Mesenteric Artery ◽  
Splanchnic Circulation ◽  
Arterial Blood Flow ◽  
Intraabdominal Pressure ◽  
Arterial Blood ◽  
Baseline Values ◽  
Air Insufflation

Background Intraabdominally insufflated carbon dioxide (CO2) during laparoscopy may have a specific effect on splanchnic circulation that may be unrelated to the effects of increased intraabdominal pressure alone. Therefore, the influences of insufflation with CO2 versus air on splanchnic circulation were compared. Methods Pigs were chronically instrumented for continuous recording of mesenteric artery, portal venous, inferior vena cava, and pulmonary arterial blood flow and portal venous pressure. After induction of anesthesia, CO2 or air was insufflated in 14 and 10 pigs, respectively. With the pigs in the supine position, intraabdominal pressure was increased in steps of 4 mmHg up to 24 mmHg by graded gas insufflation. Results During air insufflation, mesenteric artery vascular resistance was unchanged, whereas mesenteric arterial blood flow decreased with increasing intraabdominal pressure. Shortly after CO2 insufflation to an intraabdominal pressure of 4 mmHg, mean arterial pressure, mesenteric arterial blood flow, and mesenteric arterial vascular resistance were increased by 21%, 12% and 9%, respectively. Subsequently, with the onset of CO2 resorption in the third minute, mean arterial pressure declined to baseline values and mesenteric arterial vascular resistance declined to 85% of baseline values, whereas mesenteric arterial blood flow continued to increase to a maximum of 24% higher than baseline values. At steady-state conditions during CO2 insufflation, mesenteric arterial blood flow was increased up to an intraabdominal pressure 16 mmHg but decreased at higher intraabdominal pressures. Conclusions In contrast to air insufflation, intraabdominal insufflation of CO2 resulted in a moderate splanchnic hyperemia at an intraabdominal pressure < or = 12 mmHg. At higher intraabdominal pressure values, pressure-induced changes became more important than the type of gas used.

Tissue pressure as a causal factor in the autoregulation of blood flow in the isolated perfused kidney

1959 ◽  
Vol 197 (2) ◽  
pp. 309-312 ◽  
Author(s):  
Lerner B. Hinshaw ◽  
Stacey B. Day ◽  
Curtis H. Carlson
Keyword(s):  
Blood Flow ◽  
Arterial Pressure ◽  
Renal Artery ◽  
Interstitial Pressure ◽  
Tissue Pressure ◽  
Vascular Volume ◽  
Flow Through ◽  
Vascular Beds ◽  
The Difference ◽  
Bowman's Capsule

Experiments were performed on isolated perfused dog kidneys to determine relationships between tissue pressure, vascular volume, ‘over-all’ and ‘intraorgan’ vascular resistances. Results indicate that autoregulation of renal blood flow is brought about by disproportionately large increases in extravascular pressure. Since extravascular and intravascular pressures are opposing forces there is progressively less vascular distention with increases in arterial pressure as the increments in extravascular pressures approach the increments in intravascular pressures. The effective propellent force of blood flow through the kidney is thought to be the difference between the renal artery pressure and extravascular pressure. Vascular resistances calculated on this basis showed no significant changes throughout the range of autoregulation in four of the six experiments. It is proposed that the extravascular pressure within Bowmans capsule may exceed the renal interstitial pressure, and when the effects of renal extravascular pressures within and without Bowman's capsule are taken into account in the calculation of intrarenal vascular resistance, the pressure-flow relations of the kidney will be similar to those of other vascular beds.

Pre- and postglomerular resistance changes in the isolated perfused kidney

1960 ◽  
Vol 199 (5) ◽  
pp. 923-926 ◽  
Author(s):  
Lerner B. Hinshaw ◽  
Robert D. Flaig ◽  
Curtis H. Carlson ◽  
Nguyen K. Thuong
Keyword(s):  
Blood Flow ◽  
Renal Artery ◽  
Renal Blood Flow ◽  
Vascular Resistance ◽  
Combined Effects ◽  
Peritubular Capillary ◽  
Tissue Pressure ◽  
Capillary Pressures ◽  
Resistance Data ◽  
Ureteral Occlusion

The objective of the present study was to evaluate the relative roles of pre- and postglomerular vascular resistance changes in the autoregulation phenomenon. Experiments were performed on isolated dog kidneys perfused during ureteral occlusion. Ureteral pressures were assumed to approximate Bowman capsule extravascular pressure. As renal artery pressure was progressively elevated through the autoregulatory range, ureteral, intrarenal venous, and tissue pressures were measured; glomerular and peritubular capillary pressures were estimated, and pre- and postglomerular resistances were calculated. Results indicate that autoregulation of renal blood flow is brought about by the combined effects of increased tissue pressure and Bowman capsule extravascular pressure. Progressive increases in postglomerular resistance are responsible for the rise in ‘over-all’ renal resistance. Data provide evidence for the absence of the ‘myogenic reflex’ as a causal factor in autoregulation. Results are in agreement with previous reports of Winton and Gómez regarding glomerular pressure estimations and renal segmental resistance calculations.

INTERRELATIONSHIPS OF MATERNAL AND FETAL CIRCULATIONS

PEDIATRICS ◽  
1961 ◽  
Vol 27 (4) ◽  
pp. 627-635
Author(s):  
Forrest H. Adams ◽  
Nicholas Assali ◽  
Marjorie Cushman ◽  
Allan Westersten
Keyword(s):  
Blood Flow ◽  
Body Weight ◽  
Arterial Pressure ◽  
Umbilical Cord ◽  
Umbilical Vein ◽  
In Utero ◽  
Significant Rise ◽  
Arterial Blood Flow ◽  
Arterial Blood ◽  
Significant Change

Epinephrine and norepinephrine injected intravenously into pregnant ewes produced a prompt increase in maternal arterial pressure but a significant and sustained decrease in uterine arterial blood flow. Angiotensin injected intravenously into pregnant ewes produced a prompt increase in maternal arterial pressure (similar to epinephrine and norepinephrine) and an increase in uterine arterial blood flow. In the doses used, epinephrine, norepinephrine and angiotensin injected intravenously into pregnant ewes produced no significant observable effects on the arterial pressure and blood flow in the umbilical cord on heart rate in the fetus. Epinephrine and norepinephrine injected in the umbilical vein of lambs in utero produced a prompt and significant rise in umbilical arterial pressure and umbilical arterial flow only when large doses (five times effective adult doses/kg body weight) were used. Effective adult doses (kg body weight) injected into lambs in utero produced no significant change in arterial pressure or blood flow in the fetus. Angiotensin injected intravenously into lambs in utero produced no significant change in arterial pressure or blood flow in the umbilical cord. Vasoactive drugs injected into the mother on into the fetus did not appear to cross the placenta in either direction in physiologically effective amounts.

Mechanism of action of vasoconstrictor responses to atriopeptin II in conscious SHR

1985 ◽  
Vol 249 (6) ◽  
pp. R781-R786 ◽  
Author(s):  
R. W. Lappe ◽  
J. A. Todt ◽  
R. L. Wendt
Keyword(s):  
Blood Flow ◽  
Arterial Pressure ◽  
Vascular Resistance ◽  
Regional Blood Flow ◽  
Sympathetic Nerves ◽  
Spontaneously Hypertensive ◽  
Regional Vascular Resistance ◽  
6 Hydroxydopamine ◽  
Renal Vascular ◽  
Renal Sympathetic

Previous studies have demonstrated that infusion of synthetic atriopeptin II (AP II) lowered arterial pressure, reduced regional blood flow, and increased total peripheral and regional vascular resistances in conscious spontaneously hypertensive rats (SHR). This study was designed to examine the mechanism(s) involved in regional vasoconstrictor responses to AP II. In these experiments, hemodynamic actions of AP II were examined in control, 6-hydroxydopamine-treated (chemically sympathectomized), and renal-denervated groups of instrumented conscious SHR. Infusion of AP II (1 microgram X kg-1 X min-1) caused similar reductions in mean arterial pressure in control (-22 +/- 2 mmHg), chemically sympathectomized (-23 +/- 2 mmHg), and renal-denervated (-23 +/- 3 mmHg) SHR. In control SHR, AP II infusion reduced renal (-20 +/- 3%), mesenteric (-26 +/- 2%), and hindquarters (-18 +/- 10%) blood flow and increased regional vascular resistance in all three beds. Chemical sympathectomy prevented the fall in renal blood flow (RBF) and significantly abolished the regional vasoconstrictor responses to AP II infusion. In unilateral renal-denervated groups of SHR, AP II reduced renal vascular resistance (RVR) -11 +/- 3% but failed to alter RBF (-3 +/- 1%) in denervated kidneys. In contrast, RVR increased (20 +/- 7%) and RBF was significantly reduced (-29 +/- 3%) in contralateral-innervated kidneys. This study demonstrated that chemical or surgical destruction of renal sympathetic nerves abolished AP II-induced increases in RVR. These data further indicate that in conscious SHR the regional vasoconstrictor responses to AP II infusion appear to be mediated by increases in sympathetic tone rather than through direct vascular actions of AP II.

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