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Biomedical subjects

V D Deshmukh

Publications and source records attributed to V D Deshmukh.

33 records · Page 2Linked to original sources
PubMed1976

Effect of acetylcholine on cerebral circulation.

Effects of intravertebral, intracarotid, and intravenous infusion of acetylcholine on cerebral blood flow (CBF) and metabolism was studied in 17 baboons anesthetized with pentobarbital. We measured CBF by the bilateral jugular venous outflow technique using two electromagnetic flowmeters. Effect of acetylcholine infusion on cerebral vascular response to hypercapnia was also assessed. Intravertebral infusion of acetylcholine (0.01 mg/kg/min) increased CBF by 27% and cerebral metabolic rate for oxygen by 19% and decreased cerebral vascular resistance by 25%. On intracarotid injection of acetylcholine, only an 8% increase in CBF was observed, and intravenous infusion produced no change in the parameters observed. Acetylcholine administered by any of the three routes did not enhance the CBF response to hypercapnia. Increase in CBF on intravertebral administration of acetylcholine is associated with an arousal effect and an increase in cerebral metabolism.

Acetylcholine↗
PubMed1975

Central cholinergic control of cerebral blood flow in the baboon. Effect of cholinesterase inhibition with neostigmine on autoregulation and CO2 responsiveness.

Cerebral autoregulation and vastomotor responsiveness to carbon dioxide (CO2) were measured quantitatively by the use of the autoregulation index and chemical index, respectively, in normal baboons before and after intravertebral and intracarotid infusion of the anticholinesterase agent, neostigmine methylsufate (Prostigmin). Continuous measurements were made of cerebral blood flow (measured as bilateral internal jugular venous outflow), arterial and cerebral venous pO2 and pCO2, cerebral arteriovenous oxygen differences, and endotracheal CO2. The effect of intravertebral infusion of neostigmine (12.5 mug/kg body weight) was compared to intravertebral infusion of neostigmine (25 mug/kg body weight) for assessment of any specific action of the drug on a hypothetical cholinergic vasomotor center, presumed to be located in the territory of the vertebrobasilar supply. No significant or persistent changes in cerebral blood flow (CBF) and cerebral metabolic rate for oxygen (CMRO2) followed either intravertebral or intracarotid infusion of neostigmine. Cerebral vascular resistance (CVR) and cerebral perfusion pressure (CPP), however, decreased significantly after intravertebral infusion. Cerebral autoregulatory vasoconstriction during increases of CCP was significantly reduced following both intravertebral and intracarotid infusion. Cerebral autoregulatory vasodilatation was not altered as CPP was lowered. Cerebral vasodilatory reactivity to CO2 inhalation was significantly enhanced following intravertebral neostigime but not following intracarotid neostigmine. Cerebral vasoconstrictive response to hyperventilation was not influenced by neostigmine. These results support the view that central cholinergic cerebrovascular influences exist, and are vasodilatory in nature.

Acetylcholine↗
PubMedDate not supplied

Effect of beta-adrenergic blockade with propranolol on cerebral blood flow, autoregulation and CO2 responsiveness.

Cerebral autoregulation and vasomotor responsiveness to carbon dioxide were measured quantitatively in normal baboons and after intravertebral or intravenous of the beta-adrenergic blocking agent, propranolol hydrochloride (Inderal). Continuous measurements were made of cerebral blood flow (CBF: measured as bilateral internal jugular venous outflow using an electromagnetic flowmeter), cerebral perfusion pressure (CPP), arterial Po2 and Pco2 and venous Po2, cerebral arteriovenous oxygen difference and endotracheal Pco2. The autoregulation index (A.I. = deltaCBF/deltaCPP) and the chemical index (C.I.= deltaCBF/deltaPaco2), were used as quantitative measures.

Animals↗
PubMedDate not supplied

Effect of cerebrospinal fluid removal on cerebral blood flow and metabolism in patients with Alzheimer's disease versus recent stroke.

Cerebral hemispheric blood flow (HBF) and metabolism were measured before and after withdrawal of 20 to 30 ml of cerebrospinal fluid (CSF) over a 10-minute interval in eight patients with recent cerebral infarction and in four patients with Alzheimer's disease (AD). Immediately after CSF removal HBF decreased significantly in the AD group (-14%) but showed no significant change in the stroke group (-5%). There was rapid reduction in cerebral venous O2 content and some increase in cerebral venous PCO2 appearing within 60 seconds of CSF withdrawal, interpreted as a rapid reduction of cerebral blood flow (CBF) as judged by cerebral A-VO2 differences. The reduction in CBF was confirmed by the hydrogen clearance method. Reduction of CBF in response to lowering CSF pressure is presumably of neurogenic origin since it was rapid and occurred without changes in PaCO2 or MABP. Furthermore, measurement of HBF demonstrated that cerebral metabolism constant after CSF removal. It is postulated that in AD, reduction of HBF following CSF withdrawal is mediated by a disordered neurogenic veno-arterial vasoconstriction reflex which is stimulated by rapid reduction in CSF pressure (CSFP). In patients with stroke, when cerebral perfusion pressure is increased by lowering CSFP, CBF is maintained constant most likely by a physiological cerebral veno-arterial vasoconstrictive reflex. Apparently, this vasocontrictive reflex becomes excessive in Alzheimer's disease, possibly due to cerebral neurogenic imbalance.

Aged↗
PubMedDate not supplied

An ultrastructural assessment of an embolic method of producing cerebral ischemia.

This study presents ultrastructural confirmation of the embolic method of producing an ischemic lesion. The embolic method was shown to produce more advanced parenchymal changes than those reported for the same postocclusion period following vascular clipping. With this method there was less alteration in the morphological intergrity of occluded extraparenchymatous areas of the arterial bed, especially in the associated nerve bundles.

Animals↗
PubMedDate not supplied

Effect of cerebrospinal fluid removal on cerebral blood flow and metabolism in the baboon: influence of tyrosine infusion and cerebral embolism on cerebrospinal fluid pressure autoregulation.

Cerebral blood flow (CBF) and metabolism were measured before and after withdrawal of 5 to 6 ml of cerebrospinal fluid (CSF) in 17 baboons. The measurements were made before and after infusion of tyrosine, the precursor amino acid of the putative neurotransmitters, dopamine and norepinephrine, in the brain. The same observations were made in another experimental group, i.e., before and after acute cerebral multiembolization induced by microfil emboli. In the steady state CBF was unaltered following reduction of intracranial pressure by removal of CSF. After infusion of tyrosine, CBF was decreased, and cerebrovascular resistance increased significantly on removal of CSF. Cerebral embolization did not influence changes in CBF at reduced intracranial pressure. It appears that the cerebral resistance vessels constrict following reduction of intracranial pressure by removal of CSF and that cerebrospinal fluid pressure-CBF autoregulatory mechanisms are resistant to cerebral ischemia induced by middle cerebral artery embolization.

Animals↗
PubMedDate not supplied

Improved method for noninvasive measurement of regional cerebral blood flow by 133Xenon inhalation. Part I: description of method and normal values obtained in healthy volunteers.

A clinical method for noninvasive measurement of regional cerebral blood flow (rCBF) and blood volume (rCBV) is described, based on Obrist's 10 minute, desaturation method after 1 minute inhalation of 133Xe. Sixteen collimated probes are placed over both hemispheres and brain stem-cerebellar regions. End-tidal 133Xe curves are used for correction of recirculation. KEV discriminators are set to record gamma and x-ray activity separately. Values are printed out automatically by a computer on a brain map. Extracerebral contamination is reduced by 1) computing curves from gamma activity, 2) applying pressure on the scalp beneath the probes, 3) 1 minute inhalation of 133Xe and recording desaturation curves for 10 minutes, thereby minimizing slow clearance from extracranial tissues. Normal values for both fast and slow compartments are reproducible and are in good agreement with the carotid injection method. The speech dominant hemishpere has higher flow than the right under conditions described. Posterior portions of the cranium over the cerebellum and brain stem appear to have higher flow gray values than the cerebral cortex. Gray matter flow decreases with advancing age.

Adult↗