Independent control of mucosal and total airway blood flow during hypoxemia

In the larger airways, the blood circulation forms a subepithelial (mucosal) and outer (peribronchial) microvascular network. This raises the possibility that blood flow in these two networks is regulated independently. We used hypoxemia as a stimulus to induce changes in tracheal mucosal blood flow normalized for systemic arterial pressure (Qtr n) measured with an inert soluble gas technique and total bronchial blood flow (Qbr) and normalized Qbr (Qbrn) measured with an electromagnetic flow probe in anesthetized sheep. Fifteen minutes of hypoxemia [PO2 40 +/- 7 (SD) Torr] decreased mean Qtr n from 1.1 +/- 0.4 to 0.8 +/- 0.4 ml.min-1.mmHg-1.10(2) (-27%; P less than 0.05; n = 7) and increased mean Qbr n from 12.1 +/- 3.2 to 17.1 +/- 5.4 ml.min-1.mmHg-1.10(2) (+41%; P less than 0.05; n = 6). The rise in Qbr correlated with cardiac output (r = 0.68; P less than 0.05). Phentolamine pretreatment (0.1 mg/kg iv) blunted the hypoxemia-related decrease of mean Qtr n (-8%; P = NS). Tyramine (2.5 mg) applied locally to the trachea decreased mean Qtr n significantly after 30 and 45 min by 31 and 19%, respectively (P less than 0.05). 6-Hydroxydopamine (0.2 mg 4 times for 1 h locally applied) prevented the hypoxemia-induced as well as local tyramine-induced decrease in mean Qtr n (0 and 0%).(ABSTRACT TRUNCATED AT 250 WORDS)

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Laser-Doppler measurement of tracheal mucosal blood flow: comparison with tracheal arterial flow

Journal of Applied Physiology ◽

10.1152/jappl.1991.70.1.274 ◽

1991 ◽

Vol 70 (1) ◽

pp. 274-281 ◽

Cited By ~ 8

Author(s):

D. R. Corfield ◽

M. E. Deffebach ◽

I. Erjefalt ◽

R. O. Salonen ◽

S. E. Webber ◽

...

Keyword(s):

Blood Flow ◽

Mucosal Blood Flow ◽

Laser Doppler ◽

Doppler Measurement ◽

Tracheal Mucosa ◽

Doppler Flowmetry ◽

Arterial Perfusion ◽

Arterial Inflow ◽

Electromagnetic Flow Probe ◽

Tracheal Mucosal Blood Flow

Blood flow in the tracheal mucosa (Qm) has been measured by laser-Doppler flowmetry in anesthetized sheep and dogs. The values have been compared with tracheal arterial inflow (Qtr) by use of an electromagnetic flow probe and with tracheal arterial perfusion pressure (Ptr) produced by mechanical perfusion. Changes in blood flow were caused by injections of methacholine, phenylephrine, and histamine into the perfusion circuit. These interventions produced a range of measurements for each animal. Correlations of Qm against Qtr were significant in two of five animals (R = 0.03–0.93); correlations of Qm against Ptr were significant in two of four animals (R = 0.56–0.96). Percent changes in Qtr were generally much larger than those of Qm, and there was considerable variability between Qm and either Qtr or Ptr. Qm reflected the same vascular changes as Ptr or Qtr in 28 interventions and showed an opposing change in 4 cases. In 11 interventions, changes measured by Ptr or Qtr were not reflected by any changes in Qm. Thus qualitative changes in tracheal perfusion measured with these methods were usually the same; quantitatively the three methods showed great differences. These differences may reflect different regulatory mechanisms in various components of the tracheal vasculature or different technical aspects of the methods used.

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Direct Fick application for measurement of cardiac output in rat

Journal of Applied Physiology ◽

10.1152/jappl.1976.40.5.849 ◽

1976 ◽

Vol 40 (5) ◽

pp. 849-853 ◽

Cited By ~ 17

Author(s):

G. M. Walsh ◽

M. Tsuchiya ◽

E. D. Frohlich

Keyword(s):

Blood Flow ◽

Cardiac Output ◽

Electromagnetic Flowmeter ◽

Flow Probe ◽

Electromagnetic Flow ◽

Cardiac Output Determination ◽

Electromagnetic Flow Probe ◽

Simultaneous Comparison ◽

Cardiac Output Measurements

The direct Fick procedure for cardiac output determination in rat was validated by simultaneous comparison with electromagnetic flowmeter techniques. Significant coefficients of correlation were obtained between absolute cardiac output values (r = 0.789, P less than 0.001), increases (r = 0.768, P less than 0.001) and decreases (r = 0.672, P less than 0.01) in cardiac output detected by the two methods. As demonstrated in other species, cardiac output values of the Fick procedure in the rat were between 40 and 58% greater than respective electromagnetic flow probe values; however, percent changes in cardiac output obtained by the two methods were similar. The larger values of cardiac output obtained by the direct Fick method may be related, to a great extent, to the distribution of blood flow to the coronary and bronchial circulations. Fick cardiac output measurements were reproducible within rats, and the degree of variation in values among rats was similar to that obtained with the flowmeter procedure. The result indicate that the Fick meth od provides a valid estimation of cardiac output in the rat, with the ability to detect moderate changes (22–36%) in cardiac output.

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Endotracheal cuff pressure and tracheal mucosal blood flow: endoscopic study of effects of four large volume cuffs

BMJ ◽

10.1136/bmj.288.6425.1237-a ◽

1984 ◽

Vol 288 (6425) ◽

pp. 1237-1237 ◽

Cited By ~ 1

Author(s):

D Honeybourne

Keyword(s):

Blood Flow ◽

Large Volume ◽

Cuff Pressure ◽

Mucosal Blood Flow ◽

Endoscopic Study ◽

Tracheal Mucosal Blood Flow

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Endotracheal Cuff Pressure and Tracheal Mucosal Blood Flow

Survey of Anesthesiology ◽

10.1097/00132586-198502000-00026 ◽

1985 ◽

Vol 29 (1) ◽

pp. 27

Author(s):

R. D. SEEGOBIN ◽

G. L. VAN HASSELT

Keyword(s):

Blood Flow ◽

Cuff Pressure ◽

Mucosal Blood Flow ◽

Tracheal Mucosal Blood Flow

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Lingual, splanchnic, and systemic hemodynamic and carbon dioxide tension changes during endotoxic shock and resuscitation

Journal of Applied Physiology ◽

10.1152/japplphysiol.00243.2004 ◽

2005 ◽

Vol 98 (1) ◽

pp. 108-113 ◽

Cited By ~ 20

Author(s):

Jorge A. Guzman ◽

Mathew S. Dikin ◽

James A. Kruse

Keyword(s):

Blood Flow ◽

Cardiac Output ◽

Endotoxic Shock ◽

Mucosal Blood Flow ◽

Canine Model ◽

Endotoxin Shock ◽

Carbon Dioxide Tension ◽

Systemic Hemodynamic ◽

Hemodynamic Variables ◽

Blood Flow Patterns

Sublingual and intestinal mucosal blood flow and Pco2 were studied in a canine model of endotoxin-induced circulatory shock and resuscitation. Sublingual Pco2 (PsCO2) was measured by using a novel fluorescent optrode-based technique and compared with lingual measurements obtained by using a Stowe-Severinghaus electrode [lingual Pco2 (PlCO2)]. Endotoxin caused parallel changes in cardiac output, and in portal, intestinal mucosal, and sublingual blood flow (Q̇s). Different blood flow patterns were observed during resuscitation: intestinal mucosal blood flow returned to near baseline levels postfluid resuscitation and decreased by 21% after vasopressor resuscitation, whereas Q̇s rose to twice that of the preshock level and was maintained throughout the resuscitation period. Electrochemical and fluorescent Pco2 measurements showed similar changes throughout the experiments. The shock-induced increases in PsCO2 and PlCO2 were nearly reversed after fluid resuscitation, despite persistent systemic arterial hypotension. Vasopressor administration induced a rebound of PsCO2 and PlCO2 to shock levels, despite higher cardiac output and Q̇s, possibly due to blood flow redistribution and shunting. Changes in PlCO2 and PsCO2 paralleled gastric and intestinal Pco2 changes during shock but not during resuscitation. We found that the lingual, splanchnic, and systemic circulations follow a similar pattern of blood flow variations in response to endotoxin shock, although discrepancies were observed during resuscitation. Restoration of systemic, splanchnic, and lingual perfusion can be accompanied by persistent tissue hypercarbia, mainly lingual and intestinal, more so when a vasopressor agent is used to normalize systemic hemodynamic variables.

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Relation between intestinal motility and mesenteric blood flow in the conscious dog

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1984.246.2.g108 ◽

1984 ◽

Vol 246 (2) ◽

pp. G108-G113 ◽

Cited By ~ 2

Author(s):

J. Fioramonti ◽

L. Bueno

Keyword(s):

Blood Flow ◽

Mesenteric Artery ◽

Intestinal Content ◽

Flow Profile ◽

Mesenteric Blood Flow ◽

Flow Probe ◽

Postprandial Period ◽

Conscious Dog ◽

Cyclic Variations ◽

Electromagnetic Flow Probe

Blood flow in a mesenteric artery and electrical activity of the corresponding segment of jejunum or ileum were simultaneously measured in eight conscious dogs. Each was fitted chronically with an electromagnetic flow probe and transparietal electrodes. In some dogs an intestinal cannula was placed cephalad to the segment investigated. Continuous 24-h records were obtained in each dog receiving a daily meal. Jejunal blood flow increased after the meal, decreased progressively during the postprandial period (7-12 h), and then exhibited cyclic variations associated with the occurrence of migrating myoelectric complexes (MMCs) during the next 6-10 h. The ileal blood flow increased, then remained high and nearly constant during the postprandial disorganization of the MMC pattern, and exhibited cyclic variations associated with all MMCs even when the dog was fasted for 48 h. Cyclic variations in blood flow were abolished when the intestinal content was drained through the cannula. It is concluded that in the conscious dog the blood flow profile in a mesenteric artery is associated with the motor profile of the segment. This association is due to the presence of digestive matter, probably nutrients in the jejunum and bile in the ileum.

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Endothelin resets renal blood flow autoregulatory efficiency during acute blockade of NO in the rat

AJP Renal Physiology ◽

10.1152/ajprenal.0078.2001 ◽

2001 ◽

Vol 281 (6) ◽

pp. F1132-F1140 ◽

Cited By ~ 19

Author(s):

R. Kramp ◽

P. Fourmanoir ◽

N. Caron

Keyword(s):

Blood Flow ◽

Renal Blood Flow ◽

Receptor Subtypes ◽

Receptor Blockade ◽

Flow Probe ◽

Relative Contribution ◽

No Inhibition ◽

Electromagnetic Flow Probe ◽

Bq 610

First published August 15, 2001; 10.1152/ajprenal.00078.2001.—Renal blood flow (RBF) autoregulatory efficiency may be enhanced during NO inhibition in the rat, as recently reported. Under these conditions, endothelin (ET) synthesis and release may be increased. Our purpose was therefore to determine the role of ET in RBF autoregulatory changes induced by NO inhibition. To address this point, ETA/B receptors were blocked in anesthetized rats with bosentan, or selectively with BQ-610 or BQ-788. NO synthesis was inhibited with N G-nitro-l-arginine methyl ester (l-NAME). Mean arterial pressure (MAP) was decreased after bosentan (−10 mmHg; P < 0.01) or increased after l-NAME (25 mmHg; P < 0.001). RBF measured with an electromagnetic flow probe was reduced byl-NAME (−50%) and by BQ-788 (−24%). The pressure limits of the autoregulatory plateau (PA ∼100 mmHg) and of no RBF autoregulation (Po ∼80 mmHg) were significantly lowered by 15 mmHg after l-NAME but were unchanged after bosentan, BQ-610, or BQ-788. During NO inhibition, autoregulatory resetting was completely hindered by bosentan (PA ∼100 mmHg) and by ETB receptor blockade with BQ-788 (PA ∼106 mmHg), but not by ETA receptor blockade with BQ-610 (PA ∼85 mmHg). These results suggest that the involvement of ET in the RBF autoregulatory resetting occurs during NO inhibition, possibly by preferential activation of the ETB receptor. However, the relative contribution of ET receptor subtypes remains to be further specified.

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Hemodynimic effects of systemic and central administration of clonidine in the monkey

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1975.228.4.1276 ◽

1975 ◽

Vol 228 (4) ◽

pp. 1276-1279 ◽

Cited By ~ 8

Author(s):

P Bolme ◽

RP Forsyth ◽

T Ishizaki ◽

KL Melmon

Keyword(s):

Blood Flow ◽

Cardiac Output ◽

Regional Blood Flow ◽

Systemic Arterial Pressure ◽

Intraventricular Injection ◽

Central Administration ◽

New Information ◽

Before And After ◽

Microsphere Method ◽

Radioactive Microsphere Method

Systemic and regional hemodynamic changes were measured in restrained, conscious rhesus monkeys with indwelling arterial and venous catheters before and after clonidine (5 and 15 mug/kg) was slowly infused intravenously or smaller doses (2 mug/kg) were injected into a lateral cerebral ventricle. Dye-dilution cardiac outputs and the complete distribution of cardiac output were obtained intermittently with the use of the radioactive microsphere method. After the higher intravenous dose and the intraventricular injection, systemic arterial pressure was significantly lowered for 30-45 min. Both of these groups had similar changes in the redistribution of cardiac output and blood flow that outlasted the hypotensive period. Blood flow was maintained or increased in the hepatic and renal arteries at the expense of skin; flow to skeletal muscle and brain also decreased during the first hour. These data support previous studies that indicate that the primary action of clonidine is in the central nervous system and, in addition, add new information about the regional blood flow changes evoked by clonidine.

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Effects of khellin on coronary blood flow and related metabolic functions

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1959.196.2.391 ◽

1959 ◽

Vol 196 (2) ◽

pp. 391-393 ◽

Cited By ~ 6

Author(s):

Richard L. Farrand ◽

Steven M. Horvath

Keyword(s):

Blood Flow ◽

Cardiac Output ◽

Coronary Blood Flow ◽

Control Period ◽

Systemic Arterial Pressure ◽

Arterial Oxygen ◽

Arterial Oxygen Content ◽

Fick Principle ◽

Metabolic Functions ◽

Pulmonary Arterial

Khellin, a drug employed as a coronary dilator, was tested to determine its effects on the cardiovascular system of the dog. Ten mongrel dogs were anesthetized with Nembutal and, after control observations were made, given an intravenous administration of 1 mg/kg body weight of khellin. Coronary blood flow and cardiac output samples were drawn during the control period and at 10, 40 and 80 minutes after administration of the drug Cardiac output was calculated by the direct Fick principle and coronary blood flow by the nitrous oxide method. There was a significant (5%) increase in the arterial oxygen content during the 10- and 40-minute intervals, but no change was observed at 80 minutes. An increase in arterial-mixed venous oxygen difference occurred at 40 and 80 minutes. No change in systemic arterial pressure or cardiac output was noted at any time. Coronary blood flow had decreased slightly at 80 minutes. A significant decrease in carbon dioxide content of the arterial, pulmonary arterial and coronary sinus blood was observed, possibly as a consequence of hyperventilation. Khellin appeared to alter the metabolism of the myocardial and splanchnic tissues.

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