Arginine vasopressin V1-antagonist and atrial natriuretic peptide reduce hemorrhagic brain edema in rats.

Background And Purpose: Injection of arginine vasopressin into the cerebral ventricles in animals with brain injury increased brain water, whereas injection of atrial natriuretic peptide reduced water content. Therefore, to determine the role of endogenous arginine vasopressin in brain edema, we attempted to inhibit edema from a hemorrhagic lesion with an arginine vasopressin V1 receptor antagonist or atrial natriuretic peptide.

Methods: Adult Sprague-Dawley rats with hemorrhages induced by 0.

The amplitude of circadian oscillations: temperature dependence, latitudinal clines, and the photoperiodic time measurement.

This paper develops several propositions concerning the lability of the amplitude of Drosophila circadian pacemakers. The first is that the amplitude of the pacemaker's motion, unlike its period, is markedly temperature-dependent. The second is that latitudinal variation in pacemaker amplitude (higher in the north) is responsible for two very different sets of observations on Drosophila circadian systems at successively higher latitudes.

Vasopressin-induced brain edema is mediated by the V1 receptor.

Arginine vasopressin-containing nerve fibers release AVP at extrahypothalamic sites where the hormone appears to regulate brain water. To determine its role in brain edema, we intracerebrally infused AVP, thus bypassing the blood-brain barrier. Thirteen adult cats had 2 mU (5 ng) of AVP infused into the caudate nucleus in 4 microliters CSF: 2 microliters at the start of the experiment and 2 microliters at 2 hr of a 4-hr experiment.

Autoradiographic patterns of brain interstitial fluid flow after collagenase-induced haemorrhage in rat.

Cerebral oedema accompanies intracerebral haemorrhage. We induced intracranial bleeding by the intracerebral injection of bacterial collagenase. There was oedema observed both at the haematoma site in the caudate/putamen and bilaterally in the hippocampal regions.

The effect of arginine vasopressin and V1 receptor antagonist on brain water in cat.

Arginine vasopressin (AVP) is important in brain water regulation. To better understand the effect of AVP released by extrahypothalamic fibers in brain, we microinfused AVP into intact brain and studied its effect on brain water and electrolytes. Adult cats had 5 ng of AVP infused into the caudate nuclei.

Selective effect of mannitol-induced hyperosmolality on brain interstitial fluid and water content in white matter.

We studied the effect of mannitol-induced hyperosmolality on brain interstitial fluid (ISF) by autoradiography. Adult cats underwent intracerebral infusion of the extracellular marker, 14C-sucrose. Nine animals were given 2g/kg of mannitol intravenously, and another nine animals without mannitol were controls.

Determinants of osmotic phenomena created by an isolated change in extracellular solute in anuria.

The magnitude of the osmotic fluid shifts between extracellular and intracellular compartments and the changes in solute concentration that follow a change in extracellular solute are determined by the following factors: (1) the rate constant of total body osmotic fluid transfer, (2) the change in the amount of solute per liter of initial extracellular volume, (3) the initial ratio of intracellular to extracellular volume, which is usually determined by the state of extracellular volume (for the same change in the amount of solute per liter of initial extracellular volume, the changes in both extracellular volume and osmolality are greater in edematous than nonedematous states) and (4) the initial osmolality of body fluids (comparatively, the lower the initial osmolality, the larger the osmotic fluid shifts will be). However, the magnitude of the change in osmolality will be the same regardless of initial osmolality, if the other determinants are the same. If the determining factors are known, formulae applied in clinical medicine to predict the changes in solute concentration are theoretically sound.

Effect of vasopressin on ependymal and capillary permeability to tritiated water in cat.

Ependymal cells line the cerebral ventricles forming the interface that separates the cerebrospinal (CSF) and interstitial fluids (ISF). Extracellular molecules move between ependymal cells, whereas lipid soluble molecules pass both between and through cells. We measured the transfer of tritiated water (TOH) from CSF to blood across the ependymal and capillary interfaces by ventriculocisternal (VC) steady-state tissue clearance.

Pathophysiology of periventricular tissue changes with raised CSF pressure in cats.

Intraventricular pressure (IVP) is increased in the early stages of acute hydrocephalus. Pressure falls, however, when compensatory routes for cerebrospinal fluid (CSF) absorption develop. In order to better understand the pathophysiology of acute hydrocephalus, the authors performed ventriculocisternal perfusions on adult cats with outflow pressures maintained at either -5, 20, or 40 cm H2O.

Time course of blood nerve barrier reconstitution after sectioning: implications for xenograft studies.

The time course of blood-nerve barrier recovery in mouse nerves was studied after proximal and distal segmental sciatic sections. Transfer constants for uptake of isotopically labeled sucrose and urea were determined. Sectioned segments were examined ultrastructurally.

Effects of ethinyl estradiol on pharmacokinetics of meperidine and pentobarbital in the rat.

Effects of estrogen administration on in vivo hepatic microsomal drug metabolism have been frequently assessed, but there has been little study of the effects of estrogen treatment on in vivo drug pharmacokinetics. After administration of ethinyl estradiol (5 mg/kg daily for 5 days), meperidine and pentobarbital pharmacokinetics were determined both in vivo and in the isolated perfused rat liver. Estrogen pretreatment caused a 45% reduction in systemic meperidine clearance in vivo and perfusate disappearance of both meperidine and its major metabolite, normeperidine, was slower in isolated liver experiments from ethinyl estradiol-treated animals as compared with propylene glycol-treated controls.

The effect of increased CSF pressure on interstitial fluid flow during ventriculocisternal perfusion in the cat.

Transependymal absorption of cerebrospinal fluid (CSF) in hydrocephalus is suggested by periventricular edema, but the necessary bulk flow of interstitial fluid (ISF) has not been found. We performed ventriculocisternal perfusions in adult cats using CSF with the extracellular marker [3H]sucrose. CSF pressure was maintained at -5(control), 20 or 40 cm H2O for 2 or 4 h.

Alterations in pentobarbital and meperidine pharmacokinetics induced by bile duct ligation in the rat.

Although impaired microsomal drug metabolism has been demonstrated in response to bile duct ligation, there has been little previous assessment of the effects of extrahepatic biliary obstruction on drug pharmacokinetics in vivo. In this study, the effects of bile duct ligation on overall disposition on pentobarbital and meperidine in the rat have been assessed in vivo and in isolated perfused rat livers. A significant reduction in clearance of both compounds was seen in response to bile duct ligation.

Alterations in pentobarbital pharmacokinetics in response to parenteral and enteral alimentation in the rat.

Recent in vitro observations suggest that the intestine, in addition to the liver, may be an important organ of first-pass drug metabolism. While a variety of changes in intestinal morphology and function in response to continuous parenteral and enteral nutrition have been documented, the effect of different routes of alimentation on intestinal drug metabolism has not been previously investigated. Objectives of this study were to assess the contribution of intestinal pentobarbital metabolism to overall in vivo pentobarbital pharmacokinetics in the rat and to determine if differences in pentobarbital pharmacokinetics were seen between parenterally and enterally nourished animals.

Gray and white matter brain-blood transfer constants by steady-state tissue clearance in cat.

Capillary transfer constants for gray matter have been measured by others from steady-state tissue clearance during ventriculocisternal perfusion. Similar studies in white matter, however, are complicated by the bulk flow of interstitial fluid (ISF). Recently we determined the velocity of bulk flow of ISF under normal conditions.

Bulk flow of brain interstitial fluid under normal and hyperosmolar conditions.

Although bulk flow of brain interstitial fluid (ISF) occurs with changes in hydrostatic and osmotic pressures, under normal conditions only diffusion of molecules in the ISF has been reported. Extrachoroidal cerebrospinal fluid (CSF) production and intracerebral injection studies, however, provide indirect evidence for the bulk flow of ISF under normal conditions. We studied tissue penetration profiles of an extracellular molecule in gray and white matter after 1-, 2-, 3-, and 4-h ventriculocisternal perfusions.