scholarly journals Quantitative Measurement of Cerebral Blood Flow and Cerebral Blood Volume after Cerebral Ischaemia

1986 ◽  
Vol 6 (3) ◽  
pp. 338-341 ◽  
Author(s):  
Nicholas V. Todd ◽  
Piero Picozzi ◽  
H. Alan Crockard
Keyword(s):  
Blood Flow ◽  
Surface Area ◽  
Blood Volume ◽  
Quantitative Measurement ◽  
Cerebral Blood Volume ◽  
Vessel Occlusion ◽  
Permeability Surface ◽  
Area Product ◽  
Hydrogen Clearance ◽  
Clearance Technique

CBF obtained by the hydrogen clearance technique and cerebral blood volume (CBV) calculated from the [14C]dextran space were measured in three groups of rats subjected to temporary four-vessel occlusion to produce 15 min of ischaemia, followed by 60 min of reperfusion. In the control animals, mean CBF was 93 ± 6 ml 100 g−1 min−1, which fell to 5.5 ± 0.5 ml 100 g−1 min−1 during ischaemia. There was a marked early postischaemic hyperaemia (262 ± 18 ml 100g−1 min−1), but 1 h after the onset of ischaemia, there was a significant hypoperfusion (51 ± 3 ml 100 g−1 min−1). Mean cortical dextran space was 1.58 ± 0.09 ml 100 g−1 prior to ischaemia. Early in reperfusion there was a significant increase in CBV (1.85 ± 0.24 ml 100 g−1) with a decrease during the period of hypoperfusion (1.33 ± 0.03 ml 100 g−1). Therefore, following a period of temporary ischaemia, there are commensurate changes in CBF and CBV, and alterations in the permeability–surface area product at this time may be due to variations in surface area and not necessarily permeability.

Increased Hepatocyte Permeability Surface Area Product for86Rb With Increase in Blood Flow

1997 ◽  
Vol 80 (5) ◽  
pp. 645-654 ◽  
Author(s):  
Carl A. Goresky ◽  
André Simard ◽  
Andreas J. Schwab
Keyword(s):  
Blood Flow ◽  
Surface Area ◽  
Permeability Surface ◽  
Area Product

Use of [3H]methylglucose and [14C]iodoantipyrine to determine kinetic parameters of glucose transport in rat brain

1997 ◽  
Vol 272 (1) ◽  
pp. R163-R171
Author(s):  
K. Mori ◽  
M. Maeda
Keyword(s):  
Blood Flow ◽  
Surface Area ◽  
Glucose Transport ◽  
Tissue Samples ◽  
Arterial Blood ◽  
Permeability Surface ◽  
Time Courses ◽  
Area Product ◽  
Menten Kinetic ◽  
The Brain

Local maximal velocities of transport (Tmax) and the half-maximum transport constants (KT) for glucose transport across the blood-brain barrier have been determined in local regions of the brain in normal conscious rats. [14C]iodoantipyrine and [3H]methylglucose were infused together intravenously for 2 min in rats with plasma glucose concentrations maintained at different levels, and the time courses of the tracer levels in arterial blood were measured. Local 14C and 3H concentrations were then measured in tissue samples dissected from the frozen brains. By comparing the transport-limited uptake of [3H]methylglucose with the blood flow-limited uptake of [14C]iodoantipyrine, the value of m, a factor between 0 and 10 that accounts for diffusion and/or transport limitations, was derived, and from the equation, m = 1 - PS/F (where PS is capillary permeability-surface area product and F is cerebral blood flow), the permeability-capillary surface area for methylglucose was calculated (S. S. Kety. Pharmacol. Rev. 3: 1-41, 1951). Values for Tmax and KT for glucose were calculated by application of Michaelis-Menten kinetic relationships adapted for the competition for transport between glucose and methylglucose. Tmax was determined in three representative gray structures and one white structure of the brain: Tmax was 5.3 +/- 0.3 (SD) mumol.g-1.min-1 in the gray structures and 4.3 mumol.g-1.min-1 in the white structure. KT was 3.6 +/- 0.4 (SD) mM in the gray structures and 5.9 mM in the white structure. This approach allows the simultaneous determination of local values of Tmax and KT for glucose and the rates of blood flow in various regions of the brain in conscious animals.

Transport of potassium-42 from blood to tissue in isolated mammalian skeletal muscles

1959 ◽  
Vol 197 (6) ◽  
pp. 1205-1210 ◽  
Author(s):  
Eugene M. Renkin
Keyword(s):  
Blood Flow ◽  
Surface Area ◽  
Vascular Resistance ◽  
Skeletal Muscles ◽  
Systematic Variation ◽  
Theoretical Relation ◽  
Fick Principle ◽  
Permeability Surface ◽  
Area Product ◽  
Capillary Circulation

A method is described for studying transcapillary diffusion of K42 in isolated perfused muscles of dogs. Blood flow and arteriovenous K42 differences are measured and blood-tissue clearance calculated by the Fick principle. A theoretical relation between blood flow and blood-tissue clearance is developed for a uniform circulation characterized by a constant permeability—surface area product (PS). The experimental observations conform reasonably closely to prediction. However, systematic variation in measured PS product with changes in blood flow and vascular resistance indicate that the capillary circulation is not uniform.

Kinetics of pulmonary uptake of serotonin during exercise in dogs

1996 ◽  
Vol 80 (1) ◽  
pp. 30-46 ◽  
Author(s):  
J. Dupuis ◽  
C. A. Goresky ◽  
J. L. Rouleau ◽  
G. G. Bach ◽  
A. Simard ◽  
...  
Keyword(s):  
Blood Flow ◽  
Surface Area ◽  
Blood Volume ◽  
Extravascular Lung Water ◽  
Central Blood Volume ◽  
Lung Water ◽  
Pulmonary Uptake ◽  
Average Proportion ◽  
Area Product ◽  
Kinetics Of

The multiple indicator-dilution technique was employed in the exercising dog to evaluate the effect of increasing activity on the pulmonary extraction and kinetics of removal of tracer 3H-labeled serotonin (5-HT) and on the measured central blood volume and tracer-accessible extravascular lung water. 51Cr-labeled red blood cells, 125I-labeled albumin, and 14C-labeled 1,8-octanediol were injected with labeled 5-HT at rest and at two increasing levels of exercise (lower and higher in 9 dogs). Blood flow approximately tripled at the highest level of exercise, and the central blood volume increased linearly with increasing blood flow. The tracer-accessible extravascular lung water increased in the transition from rest to low-level exercise and stabilized at an average proportion of 0.85 of the gravimetric extravascular lung water at the higher values of blood flow. The average labeled 5-HT extraction at rest was 42 +/- 11%, and this slowly decreased with increase in flow. The calculated permeability-surface area product for 5-HT increased approximately directly with increasing blood flow. We conclude that exercise results in an increase in the central blood volume that is accompanied by an increase in the tracer-accessible extravascular lung water (lung tissue recruitment) over low exercise levels, with no change at higher levels of exercise, and that the pulmonary capillary surface area subserving 5-HT uptake increases almost linearly with flow over the range of flows attained.

Endothelin-1 myocardial clearance, production, and effect on capillary permeability in vivo

1997 ◽  
Vol 273 (3) ◽  
pp. H1239-H1245 ◽  
Author(s):  
J. Dupuis ◽  
C. A. Goresky ◽  
C. P. Rose ◽  
D. J. Stewart ◽  
P. Cernacek ◽  
...  
Keyword(s):  
Blood Flow ◽  
Surface Area ◽  
Coronary Sinus ◽  
Myocardial Metabolism ◽  
Endothelin 1 ◽  
Permeability Surface ◽  
Anesthetized Dogs ◽  
Myocardial Clearance ◽  
Area Product

Myocardial metabolism of endothelin-1 (ET-1) and its effect on coronary microcirculatory exchanges were obtained in anesthetized dogs by combining the indicator-dilution technique with immunoreactive ET-1 measurements. The myocardium extracted 17.7 +/- 4.6% of tracer ET-1 (n = 12). Simultaneously measured ET-1 levels in the aorta (0.97 +/- 0.46 pg/ml) and coronary sinus (0.96 +/- 0.53 pg/ml) were not different, supporting a production of ET-1 by the heart that balances the amount extracted. Intracoronary infusion of ET-1 (5 ng.kg-1.min-1) increased coronary sinus ET-1 levels approximately 50-fold, decreased coronary blood flow per unit of interstitial space by approximately 30% (P = 0.006), and increased myocardial microcirculatory transit times (n = 6). Permeability to albumin was unaffected by ET-1, whereas the permeability-surface area product for sucrose decreased following derecruitment of myocardial capillaries. We conclude that there is a normal myocardial metabolic balance of ET-1 and that the heart marginally contributes to circulating ET-1. Pharmacological doses of ET-1 may adversely affect myocardial metabolism by reducing blood flow and the permeability-surface area product for small circulating substances.

Forelimb blood flow distribution during hypothalamic dilator response

1976 ◽  
Vol 230 (6) ◽  
pp. 1561-1568 ◽  
Author(s):  
RP Menninger ◽  
CH Baker
Keyword(s):  
Blood Flow ◽  
Surface Area ◽  
Flow Distribution ◽  
Hypothalamic Stimulation ◽  
Blood Flow Distribution ◽  
Vascular Volume ◽  
Capillary Filtration ◽  
Flow Channels ◽  
Permeability Surface ◽  
Area Product

An attempt is made to determine whether hypothalamically induced forelimb vascular dilation in the dog affects primarily exchange beds or shunt circuits. Slug injections of [131I] albumin and 86RbCl were used to measure the active vascular volume of the forelimbs and permeability surface area product (PS), respectively. Changes in total vascular volume (TVV), filtration, and capillary filtration coefficient (CFD) were measured by plethysmography. During stimulation, forelimb blood flow increased 25% and TVV increased an average 1.5 ml. There was no plethysmographic evidence of outward capillary filtration. Active vascular volume decreased 11%. PS decreased 11%, and CFC decreased 20%. These results point to a redistribution of blood flow from exchange circuits to faster flow channels. During constant-inflow perfusion, there was evidence from CFC and PS measurements that the capillary surface area was increased while active vascular volume decreased. The results observed with hypothalamic stimulation are different from those obtained with pharmacologic dilators and denervation. It is suggested that the former method has a more selective effect in lowering resistance in the faster shuntlike vessels.

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