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1.
J Neurol Neurosurg Psychiatry ; 49(3): 302-9, 1986 Mar.
Article in English | MEDLINE | ID: mdl-3083051

ABSTRACT

Cerebral blood flow (CBF) was measured in anaesthetised cats with 133Xe clearance method under normal conditions and with hyperammonaemia. Elevation of blood ammonia concentration by an intravenous infusion of ammonium acetate caused an increase in CBF and a parallel decrease in cerebrovascular resistance (CVR). These parameters reached, however, plateau at an arterial blood ammonia level exceeding 500 mumol/l. Cerebrovascular reactivity to CO2 diminished following elevation of blood ammonia concentration and at arterial blood ammonia level exceeding 500 mumol/l it was virtually abolished. In contrast, hyperammonaemia influenced neither cerebrovascular responsiveness to papaverine nor autoregulatory properties of the cerebral circulation. It is concluded, therefore, that hyperammonaemia exerts some dilatatory effect on cerebral vessels and severely impairs chemical regulation of CBF but does not elicit cerebral vasomotor paralysis.


Subject(s)
Ammonia/toxicity , Cerebrovascular Circulation , Cerebrovascular Disorders/chemically induced , Vasomotor System , Ammonia/blood , Animals , Carbon Dioxide/blood , Cats , Female , Homeostasis , Male , Papaverine , Vascular Resistance
2.
Acta Neurobiol Exp (Wars) ; 46(1): 47-56, 1986.
Article in English | MEDLINE | ID: mdl-3090861

ABSTRACT

Cerebral blood flow (CBF) and its response to hypercapnia were evaluated in cats with brainstem transected either at rostropontine (pretrigeminal preparation) or prepontine (cerveau isole preparation) level. Additionally, the effect of pentobarbital on CBF response to hypercapnia and to papaverine were examined. CBF was measured with 133 Xe intracarotid injection method. Cortical EEG activity was recorded. In rostropontine cats cerebral vessels responded with a dilatation to hypercapnia. In prepontine cats CBF response to CO2, was absent, where-as that to papaverine maintained. In rostropontine cats administration of pentobarbital, even in very low doses, caused disappearance of CBF response to hypercapnia, leaving that to papaverine. Our results support the idea that a neurogenic mechanism is involved in chemical regulation of CBF. The rostra1 part of the pontine reticular formation may be responsible for this neurogenic control.


Subject(s)
Carbon Dioxide , Cerebrovascular Circulation , Decerebrate State/physiopathology , Electroencephalography , Papaverine , Pentobarbital , Animals , Cats , Female , Male
3.
Graefes Arch Clin Exp Ophthalmol ; 223(3): 145-9, 1985.
Article in English | MEDLINE | ID: mdl-3849458

ABSTRACT

Intraocular pressure (IOP) and arterial blood pressure (BP) were recorded manometrically in normotensive Wistar Kyoto rats (NR) and stroke-prone spontaneously hypertensive rats (SHR). IOP was significantly lower in SHR (7.8 +/- 0.2 mm Hg) compared to NR (15.9 +/- 0.4 mm Hg). In NR, administration of vasoactive substances (kallikrein, bradykinin, angiotensin I and II) or bloodletting resulted in significant IOP reactions, which ran nearly parallel to the acute BP changes. In SHR, however, IOP showed little reaction after comparable changes in BP. The cause of the low IOP in SHR is unknown. It is assumed that in SHR rarefaction of arterioles and capillaries and a decrease in the compliance of eye vessels, in combination with an increase in the distensibility of the bulbus at this low IOP level, contribute to the lack of IOP response after administration of vasoactive drugs.


Subject(s)
Angiotensins/pharmacology , Blood Pressure/drug effects , Bradykinin/pharmacology , Hypertension/physiopathology , Intraocular Pressure/drug effects , Kallikreins/pharmacology , Angiotensin I/pharmacology , Angiotensin II/pharmacology , Animals , Rats , Rats, Inbred SHR , Rats, Inbred WKY , Reference Values
4.
Exp Brain Res ; 60(3): 551-8, 1985.
Article in English | MEDLINE | ID: mdl-4076376

ABSTRACT

The effect of stimulation of the medial and lateral reticulo-hypothalamic-hippocampal (RHH) systems on cerebral blood flow (CBF) and electrical activity of the hippocampus and neocortex was examined in 19 encéphale isolé cats. ECoG was recorded from posterior sigmoid gyri and marginal gyri and hippocampal activity from dorsal hippocampus. Changes in hippocampal activity were evoked by electrical stimulation of RHH systems. CBF was measured by external monitoring of the clearance of 133Xe given as a single bolus in the carotid artery. Stimulation of the lateral system resulted in desynchronisation of ECoG and hippocampal activity without changes in CBF. Stimulation of the medial system elicited desynchronisation in ECoG modulated by theta-like synchrony, theta activity in the hippocampus and a 45% CBF increase. After atropine administration, low frequency, high voltage waves appeared in both ECoG and hippocampal activity, but no change in CBF was observed. During stimulation of the medial system there were no changes in the type of electrical activity but the CBF response was still preserved (increase by 50%). Stimulation of the lateral system did not change either the type of electrical activity or the CBF. The results indicate that the two systems of neuronal pathways, which mediate two different patterns of electrical response in the dorsal hippocampus but similar ECoG activity in the neocortex, elicit different CBF responses. It is argued that the alterations of electrical activity of the neocortex and hippocampus mediated by these two pathways depend on the cholinergic system, whereas the CBF changes depend on a different mechanism.


Subject(s)
Brain/blood supply , Cerebral Cortex/physiology , Hippocampus/physiology , Hypothalamus/physiology , Action Potentials/drug effects , Animals , Atropine/pharmacology , Blood Flow Velocity/drug effects , Cats , Electric Stimulation , Electroencephalography , Neural Pathways/physiology , Time Factors
7.
Clin Exp Pharmacol Physiol ; 9(6): 631-7, 1982.
Article in English | MEDLINE | ID: mdl-7166007

ABSTRACT

1. L-Dopa induced a 56% increase in frontal cortical blood flow (fcCBF) one hour after intraperitoneal administration in stroke-prone spontaneously hypertensive rats. The treatment with carbidopa did not alter the magnitude of the response but shortened the response time to half an hour. In stroke-resistant rats and in Wistar Kyoto rats, L-dopa decreased fcCBF. This response was reversed to different degree by carbidopa pretreatment. 2. Serotonin decreased fcCBF in all groups. L-Dopa administered one hour after serotonin resulted in a recovery to the control level in SHR-SR, an increase in fcCBF in WK but the decreased flow in SHR-SP was maintained till the end of the observation time. 3. The data suggest that the stroke-prone rats have an unusual response to L-dopa and that L-dopa and this combination with a peripheral decarboxylase inhibitor may have a beneficial effect on the improvement of cerebral blood flow especially when the pre-existing level of cerebral blood flow is reduced in severe hypertension.


Subject(s)
Carbidopa/pharmacology , Cerebrovascular Circulation/drug effects , Hypertension/physiopathology , Levodopa/pharmacology , Serotonin/physiology , Animals , Blood Pressure/drug effects , Carboxy-Lyases/antagonists & inhibitors , Hydrogen/metabolism , Injections, Intraperitoneal , Levodopa/administration & dosage , Male , Rats , Rats, Inbred Strains
8.
Acta Physiol Pol ; 32(6): 713-7, 1981.
Article in English | MEDLINE | ID: mdl-7348523

ABSTRACT

Experiments were performed on partly isolated livers of guinea pigs. The effects of partial obstruction of the portal inflow and hepatic outflow on the intrahepatic circulation were studied by 133Xe bolus technique after intraportal or intraarterial tracer injection. Partial obstruction of the vena cava results in a decrease of nutritive hepatic blood flow of 21%, whereas partial obstruction of portal inflow by a decrease of only 7%. The compensation for reduced portal inflow by increased arterial input is discussed.


Subject(s)
Hepatic Artery/physiology , Liver Circulation , Portal Vein/physiology , Animals , Blood Pressure , Guinea Pigs , Vena Cava, Inferior/physiology
11.
Clin Exp Hypertens (1978) ; 3(2): 319-29, 1981.
Article in English | MEDLINE | ID: mdl-7215070

ABSTRACT

The 133Xe single bolus injection technique was used for measuring the cerebral blood flow (CBF) in spontaneously hypertensive (SHR) and normotensive rats. Their age was from 5 to 25 weeks and corresponded to the time before the initiation of the arterial blood pressure (BP) increase to the constant phase of hypertension. CBF in SHR 5 and 10 weeks of age was significantly higher than in all other groups being 155 +/- 7.2 and 151 +/- 9.3 ml/min/100 g, respectively. At 15 weeks of age the localization of the reactive products of ATP and CTP became scanty and spread over the endothelial cytoplasm. Further, at 25 weeks an enlarged number of empty pinocytic vesicles and astrocytic foot processes filled with flocculent electron dense material was found. These data suggest that the initial high CBF preceding the increase of BP can initiate the irreversible disorder of endothelial cells in brain capillaries.


Subject(s)
Brain/blood supply , Capillaries/ultrastructure , Hypertension , Animals , Blood Pressure , Male , Microscopy, Electron , Rats
13.
Acta Physiol Pol ; 31(4): 383-9, 1980.
Article in English | MEDLINE | ID: mdl-7446151

ABSTRACT

The reversibility of osmotic opening of the blood-brain barrier was studied in dogs one hour after intracarotid 3 M urea injection. At that time the permeability of cerebral blood vessels to albumin is restored as evidenced by lack of Evans blue extravasation. Despite that, the response of the urea-perfused hemisphere to changes of perfusion pressure was abnormal. Blood flow in that hemisphere followed passively blood pressure changes in contrast to the contralateral hemisphere in which the blood flow remained independent of the perfusion pressure.


Subject(s)
Blood-Brain Barrier , Capillary Permeability , Cerebrovascular Circulation , Homeostasis , Animals , Blood Pressure , Capillary Permeability/drug effects , Carotid Artery, Internal , Cerebral Cortex/blood supply , Dogs , Hypertonic Solutions , Injections, Intra-Arterial , Osmosis , Regional Blood Flow , Serum Albumin/metabolism , Urea/administration & dosage
14.
Acta Physiol Pol ; 31(3): 247-52, 1980.
Article in English | MEDLINE | ID: mdl-7446143

ABSTRACT

For measuring the cerebral blood flow (CBF) in young (5 weeks old) and adult (25 weeks old) rats the 133Xe bolus technique was used. The effect of the preparation technique on the shape of the washout curve is discussed. The values of CGFfast estimated by the two compartmental analysis were comparable to that obtained by other methods.


Subject(s)
Cerebrovascular Circulation , Xenon Radioisotopes/administration & dosage , Aging , Animals , Carotid Arteries , Injections, Intra-Arterial , Male , Plethysmography, Impedance/methods , Rats , Regional Blood Flow
15.
Q J Exp Physiol Cogn Med Sci ; 65(2): 99-104, 1980 Apr.
Article in English | MEDLINE | ID: mdl-6902965

ABSTRACT

Using the 133Xe clearance method it is shown that NH4Cl infusion into the anterior mesenteric vein decreased capillary blood flow in the liver. Phentolamine completely and propranolol partially prevented the depressive action of NH4Cl on hepatic blood flow. NH5Cl infused into the jugular vein provoked a slight increase in the hepatic blood flow. The adrenaline-like action of ammonium ion on the blood circulation in the liver region is discussed.


Subject(s)
Ammonium Chloride/pharmacology , Liver/blood supply , Sheep/physiology , Ammonium Chloride/antagonists & inhibitors , Animals , Capillaries/physiology , Depression, Chemical , Phentolamine/pharmacology , Propranolol/pharmacology , Regional Blood Flow/drug effects
18.
Acta Physiol Pol ; 30(5-6): 617-20, 1979.
Article in English | MEDLINE | ID: mdl-532672

ABSTRACT

85SR was used for the local blood flow measurements in bones. A method for dynamic analysis of the magnitude of local blood flow based on 7-min analysis of the area under the logarithmic curve was presented. The radioactivity of the tibial diaphysis was followed by a gamma-scintillation dectector focused on the area of approximately 10 mm 0. The revascularisation process during bone repair after the osteotomy of the tibial diaphysis fixed intramarrowally was observed on 14 rabbits, two and four weeks after the osteotomy. In the first two weeks following the osteotomy the process of revascularisation was significantly enhanced in a comparison to the second two weeks.


Subject(s)
Bone and Bones/blood supply , Strontium Radioisotopes , Wound Healing , Animals , Bone and Bones/physiology , Female , Male , Methods , Osteotomy , Rabbits , Regional Blood Flow , Tibia/surgery
19.
Arch Int Pharmacodyn Ther ; 237(1): 110-8, 1979 Jan.
Article in English | MEDLINE | ID: mdl-485676

ABSTRACT

The effect of unilateral intracarotid administration of 3 M urea on resting cerebral blood flow, arterial blood pressure, perfusion pressure-cerebral blood flow relation, ECoG and Evans blue permeability was tested in dogs. The injection of urea was without effect on ECoG and enhanced the arterial blood pressure temporarily. Cerebral blood flow measured 10 min after the urea injection was not affected. Extravasation of Evans blue was observed in the urea-perfused hemisphere for about 40 min following the urea administration. Cerebral perfusion pressure-blood flow relation for the urea affected hemisphere studied at the time when blood-brain barrier to protein was restored revealed loss of the normal autoregulatory response, despite that it was preserved in the control hemisphere.


Subject(s)
Cerebrovascular Circulation/drug effects , Urea/pharmacology , Animals , Blood Pressure , Blood-Brain Barrier , Dogs , Electroencephalography , Hypertonic Solutions , Time Factors , Urea/administration & dosage
20.
Acta Neurobiol Exp (Wars) ; 39(5): 335-43, 1979.
Article in English | MEDLINE | ID: mdl-575466

ABSTRACT

The effect of visual stimulation on cerebral blood flow (CBF) was studied in five cats with brainstem transection at the pretrigeminal level. The CBF was measured in the occipital and frontal cortex by external monitoring of the clearance of 133Xe. As a visual stimulus, a feather duster moving for 2 min in front of the cat’s eyes was used. This stimulus evoked an increase of CBF. In the occipital cortex the CBF increase was greater and comparable to that evoked by elevation of the arterial pCO2. Both in the occipital and frontal cortex the CBF response was positively correlated with the intensity of the ocular-following reflex and the cortical EEG arousal. It is concluded that the CBF increase was correlated with the degree of attention paid by the cat to the visual stimulus.


Subject(s)
Attention/physiology , Brain Stem/physiology , Cerebrovascular Circulation , Vision, Ocular/physiology , Animals , Cats , Humans , Wakefulness/physiology
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