scholarly journals Measurement of Local Cerebral Blood Flow in the Unanesthetized Rat Using a Hydrogen Clearance Method

1968 ◽  
Vol 23 (2) ◽  
pp. 313-324 ◽  
Author(s):  
JOSEPH L. HAINING ◽  
M. Don TURNER ◽  
RALPH M. PANTALL
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Local Cerebral Blood Flow ◽  
Hydrogen Clearance Method ◽  
Hydrogen Clearance

scholarly journals The Effect of Local Infusion of Adenosine and Adenosine Analogues on Local Cerebral Blood Flow

1989 ◽  
Vol 9 (4) ◽  
pp. 556-562 ◽  
Author(s):  
David G. L. Van Wylen ◽  
T. S. Park ◽  
Rafael Rubio ◽  
Robert M. Berne
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Receptor Activation ◽  
Local Cerebral Blood Flow ◽  
Caudate Nuclei ◽  
Adenosine Concentration ◽  
The Brain ◽  
Adenosine Receptor Activation ◽  
Dialysis Technique ◽  
Hydrogen Clearance

The purpose of this study was to determine the effects of local infusion of adenosine (ADO) and non-metabolized ADO analogues on local cerebral blood flow (CBF) and interstitial fluid (ISF) ADO levels. The brain dialysis technique was used to (a) deliver drugs locally to brain tissue, (b) estimate cerebral ISF ADO levels, and (c) measure local CBF (hydrogen clearance). Dialysis probes were implanted bilaterally in the caudate nuclei of ketamine-anesthetized rats. The probe on one side was perfused with artificial CSF while the contralateral probe was perfused with artificial CSF containing ADO ( n = 5), or the ADO agonists 2-chloroadenosine (2-CADO; n = 4) or 5'-N-ethylcarboxamide adenosine (NECA; n = 4). When ADO was included in the artificial CSF at 10−5, 10−4, or 10−3 M, a 30% increase in local CBF was detected only with 10−3 M ADO. During perfusion with ADO, dialysate inosine and hypoxanthine levels increased, indicating that the cells adjacent to the probe metabolized the exogenous ADO. With 2-CADO included in the artificial CSF at 10−6, 10−5, or 10−4 M, local CBF increased 18, 131, and 201%, respectively. Perfusion with artificial CSF containing 10−7, 10−6, or 10−5 M NECA resulted in a 35, 112, and 187% increase in local CBF, respectively. In a separate group of rats ( n = 6), perfusion with artificial CSF containing 10−6 M NECA resulted in a sustained twofold increase in local CBF and 40% decrease in dialysate adenosine concentration, both of which could be reversed by including 8-( p-sulfophenyl)-theophylline, an ADO receptor antagonist, in the artificial CSF. These results are consistent with the known vascular actions of ADO and ADO analogues and suggest that there is a basal level of ISF ADO that can be reduced by increased CBF and/or adenosine receptor activation.

Modified Thermal Diffusion Flow Probe for the Continuous Monitoring of Cortical Blood Flow

Neurosurgery ◽  
1991 ◽  
Vol 29 (4) ◽  
pp. 583-589 ◽  
Author(s):  
Naoya Kuwayama ◽  
Akira Takaku ◽  
Jun Harada ◽  
Osamu Fukuda ◽  
Shunro Endo ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Thermal Diffusion ◽  
Continuous Monitoring ◽  
Regression Line ◽  
Diffusion Flow ◽  
Thermal Probe ◽  
Local Cerebral Blood Flow ◽  
Flow Probe ◽  
Hydrogen Clearance

Abstract A small thermal diffusion flow probe has been developed to monitor the dynamic changes in cerebral blood flow in small animals. Constantan wire was used as a heat source to make a miniature probe. The pair of thermocouples used to detect the heat gradient between two gold plates was elongated to avoid heat conduction between them, and this improvement allowed us to make quantitative measurements. After several basic experiments, local cerebral blood flow was measured simultaneously, using both the modified thermal probe and the hydrogen clearance method in four rabbits. A close relationship was obtained between the local cerebral blood flow values measured by hydrogen clearance (F, ml/100g/min) and the reciprocal of the thermocouple voltage (1/V;1/mV). The regression line was F = 29111(1/V- 1/226), (r = 0.92, P<0.001). We suggest that the modified thermal probe is a reliable and quantitative means of measuring flow. In addition, another probe modified for clinical use was evaluated. Continuous monitoring of local cerebral blood flow in postoperative patients was performed, and some illustrative cases are described.

Cerebral blood flow and the thermal properties of the brain: a preliminary analysis

1989 ◽  
Vol 70 (4) ◽  
pp. 592-598 ◽  
Author(s):  
Michael Salcman ◽  
Eiji Moriyama ◽  
Henry J. Elsner ◽  
Herman Rossman ◽  
Robert A. Gettleman ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Thermal Properties ◽  
Specific Heat ◽  
Correlation Coefficient ◽  
Microwave Antenna ◽  
Microwave Antennas ◽  
Hydrogen Clearance Method ◽  
The Brain ◽  
Hydrogen Clearance

✓ Safe and effective use of hyperthermia for the treatment of brain tumors requires precise control of the distribution of temperatures (that is, the thermal field) within the tumor and within the adjacent brain. Major influences upon the distribution of temperatures include the passive thermal properties of the brain, such as its specific heat (Cb), and the contribution of cerebral blood flow (CBF). Recently, an electrical-mechanical analog model of heat flow within the brain has been developed from which an expression for CBF has been derived: CBF = Cb/(τρc) where τ is the thermal decay constant, ρ is the density of blood, and c is its specific heat. To test this model a series of experiments was carried out in adult dogs in which stereotaxically implanted microwave antennas operating at 2450 MHz, fluoro-optical thermometry probes, and platinum electrodes were used to simultaneously measure CBF by thermal washout and hydrogen clearance techniques. The correlation coefficient for estimates of CBF derived by the two methods in 52 paired observations was 0.89. Measurements of CBF were more reliable at increased distances from the microwave antenna, since CBF is sensitive to the degree of temperature elevation (ΔT). The ratio of post-heating CBF to pre-heating CBF varies linearly with ΔT and has a correlation coefficient of 0.86. When values of CBF determined by the hydrogen clearance method were employed in the above equation, it was possible to derive Cb as 0.70 ± 0.08 cal/gm-°C. Use of this value for Cb in this equation produces estimates of CBF by thermal clearance that are within 10% of the values for CBF as measured by the hydrogen clearance method. It is concluded that this model of thermal flow within the brain may have heuristic value for treatment planning and that microwave antennas and fluoro-optical probes may represent a new methodology for the clinical estimation of CBF. These methods have recently been employed in patients undergoing combined hyperthermia and chemotherapy.

Changes of blood flow in the adenohypophysis of normal and estrogen pretreated Fisher rats by tamoxifen

1989 ◽  
Vol 121 (6) ◽  
pp. 821-826 ◽  
Author(s):  
Andrzej Stawowy ◽  
Andras A. Kemeny ◽  
Jan Jakubowski
Keyword(s):  
Blood Flow ◽  
Cerebral Cortex ◽  
Cerebral Blood Flow ◽  
Arterial Pressure ◽  
Anterior Pituitary ◽  
Tamoxifen Treatment ◽  
Hydrogen Clearance Method ◽  
Pituitary Hyperplasia ◽  
F344 Rats ◽  
Hydrogen Clearance

Abstract. Blood flow was measured in the adenohypophysis and in the cerebral cortex of female F344 rats over a period of 90 min using the hydrogen clearance method. Tamoxifen, 1 mg/kg, administered iv reduced the blood flow in the adenohypophysis by 35%, whereas cerebral blood flow and arterial pressure remained unchanged. Seven days sc treatment with tamoxifen (1 mg/kg daily) had no demonstrable effect on blood flow. Anterior pituitary hyperplasia was induced in 15 rats with diethylstilbestrol containing implants. These rats responded to 7 days of sc tamoxifen treatment by 30% increase in adenohypophyseal blood flow. These results suggest that tamoxifen has a different effect on adenohypophysial circulation of the rat depending on whether it is administered in a low- or high-estrogen state.

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