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D N Krause

Publications and source records attributed to D N Krause.

48 records · Page 3Linked to original sources
PubMed1985

Long-term serial cultivation of arterial and capillary endothelium from adult bovine brain.

Cerebrovascular endothelial cells from adult bovine brain were carried successfully in long-term, serial culture. Endothelial cells were obtained from the middle and anterior cerebral arteries and from capillaries isolated from grey matter of the cerebral cortex or caudate nucleus. Capillary cells were found to grow best in RPMI 1640 with 20% fetal bovine serum. They did not require tumor-conditioned medium or matrix-coated surfaces, although fibronectin was used to enhance the initial plating efficiency of the primary cultures. The same conditions were used to support satisfactory growth of arterial endothelial cells; however they did not grow as rapidly as the cells. Retention of endothelial-specific characteristics were shown for capillary-derived cells carried up to Passage 28, arterial-derived cells up to Passage 11, and after frozen storage of both types of cultured cells. Cultures of both arterial and capillary cells stained positively for Factor VIII antigen, exhibited a nonthrombogenic surface, and produced prostacyclin in response to arachidonic acid. Arterial endothelial cells produced more prostacyclin than capillary endothelium. The capillary cells had a unique tendency to assume a ringlike morphology after subculture and sometimes formed capillarylike networks of cell cords in dense cultures. When cultured in a three-dimensional plasma clot, capillary and arterial endothelial cells, but none of the other cell types studied, organized into tubelike structures reminiscent of capillary formation in vivo. The availability of long-term cultures of cerebrovascular endothelial cells provides an opportunity to compare properties of arterial and capillary endothelium from the same tissue and to investigate such processes as angiogenesis and blood-brain barrier induction.

Animals↗
PubMed1983

Biochemical evidence for cholinergic innervation of intracerebral blood vessels.

Muscarinic cholinergic receptor sites were detected with [3H]quinuclidinylbenzilate (QNB) binding techniques in two fractions of bovine intracerebral vessels; one of the fractions contained primarily small arteries and veins with some attached capillaries, and the other one was highly enriched in capillaries. The amounts of binding were similar in equivalent vascular fractions isolated from cerebral cortex, caudate nucleus and cerebellar cortex in spite of large differences among the 3 regions in [3H]QNB binding to brain tissue. The different distribution of muscarinic receptors in brain tissue and blood vessels argues against the possibility that the receptors represent a contamination of the vascular fractions by brain parenchyma. Cerebral endothelial cells, which were isolated by treating capillaries with collagenase, bound [3H]QNB to the same extent as did cerebral capillaries. This is consistent with an endothelial localization of capillary muscarinic receptors. Choline acetyltransferase (ChAT) activity, a marker for cholinergic neurons, also was present in the vascular preparations. Within each brain region, ChAT activities in capillaries and larger vessels were similar, but significant regional differences were found for vascular ChAT activity, with the highest values in the caudate. Isolated endothelial cells contained significantly lower levels of ChAT activity than intact capillaries, suggesting a periendothelial location of the enzyme, as would also be the case for attached nerve terminals. The presence of [3H]QNB binding sites and ChAT activity in intracerebral blood vessels is consistent with an innervation of the cerebral vasculature by a cholinergic system that may regulate cerebral blood flow and capillary permeability.

Acyltransferases↗
PubMed1982

Characterization of glutamic acid decarboxylase activity in cerebral blood vessels.

Glutamic acid decarboxylase activity associated with cerebral blood vessels appears to be part of a specific cerebrovascular system involving gamma-aminobutyric acid. This activity was characterized kinetically and pharmacologically and compared with that in brain and several nonneuronal tissues. Formation of gamma-aminobutyric acid from [14C]glutamate was measured in a soluble extract of pia-arachnoid blood vessels isolated from bovine brain. The vascular activity was like brain glutamate decarboxylase in that it required pyridoxal phosphate, was completely inhibited by aminooxyacetic acid, and had a similar affinity for glutamate. Cerebrovascular decarboxylase activity differed, however, from brain decarboxylase in that it was less sensitive to sulfhydryl reagents, was stimulated by 3-mercaptopropionic and cysteic acids, and was competitively inhibited by cysteine sulfinic acid. The glutamate decarboxylase activity of the cerebral vessels was similar to that in renal cortex and mesenteric blood vessels in its responses to sulfhydryl reagents and 3-mercaptopropionic acid. These findings are consistent with previous suggestions of a nonneuronal form of the enzyme and offer the possibility that synthesis of gamma-aminobutyric acid in cerebral blood vessels can be manipulated independently from that in neuronal tissue.

Animals↗
PubMed1982

gamma-Aminobutyric acid system in cardiovascular and cerebrovascular function.

gamma-Aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the vertebrate CNS. Recent experiments have begun to delineate the roles of GABA neurons in control of both central sympathetic and parasympathetic outflows to the heart and vasculature. It is suggested that incoordination in these regions resulting from inadequate function of GABA neurons could lead to cardiac arrhythmias and large fluctuations in blood pressure that would predispose to cardiac and vascular damage. A role for GABA in cerebrovascular function is supported by the observation that specific GABA receptors and GABA-related enzymes are associated with cerebral blood vessels. It is suggested that a non-neural, indigenous GABA system in cerebral blood vessels is involved in the control of cerebrovascular tone. GABA probably plays an important role in the complex processes involved in normal regulation of cerebral circulation and its dysfunction.

4-Aminobutyrate Transaminase↗
PubMed1982

Muscarinic cholinergic receptor sites in cerebral blood vessels.

Muscarinic cholinergic receptor sites in cerebral blood vessels were analyzed directly by using radioligand binding techniques with the specific muscarinic antagonist [3H]quinuclidinyl benzilate (QNB) as ligand. Specific binding of [3H]QNB to membrane preparations from isolated bovine pia-arachnoid vessels was found to be saturable, of high affinity (Kd = 5.4 X 10(-10) M) and selectively inhibited by muscarinic antagonists (atropine) and agonists (acetylcholine, carbachol and methacholine). Scatchard and Hill plot analyses of the data indicated one class of sites for the antagonists, but two independent classes of sites were revealed with the agonists. Interestingly, the high and low affinities of the agonist sites correlated with the concentrations of agonist which have been reported to produce dilation and contraction, respectively, of isolated pial artery segments. A substantial number of specific [3H]QNB binding sites also were measured in isolated bovine cerebral microvessels providing direct evidence for muscarinic receptors in intracerebral vessels. In contrast, specific [3H]QNB binding was barely detectable in mesenteric blood vessels. Choline acetyltransferase (ChAT) activity was measured in parallel with [3H]QNB binding. The relative distribution of choline acetyltransferase was correlated with that for the binding, with the highest values observed in the intracerebral microvessels. This suggests a functional innervation of the cerebrovascular muscarinic receptors.

Animals↗
PubMed1981

Dose-conductance relationships for GABA agonists and the effect of uptake inhibitors in crayfish stretch receptor neurons.

The interaction of GABA (gamma-aminobutyric acid) and structurally-related compounds with postsynaptic GABA receptors was studied quantitatively by measuring receptor-mediated increases in membrane input conductance in isolated crayfish stretch receptor neurons (SRN). The following compounds, in order of decreasing potency, were effective agonists: muscimol greater than GABA greater than isoguvacine greater than (-)gamma-amino-beta-hydroxybutyric acid greater than beta-gu anidinopropionic acid greater than 3-aminopropanesulfonic acid greater than (+)gamma-amino-beta-hydroxybutyric acid greater than isonipecotic acid greater than THIP. A highly significant correlation was found between the log potencies for GABA agonists that were obtained in the SRN and those obtained in our laboratory using mammalian GABA receptor binding assays. Hill plot analyses of the log concentration-conductance data from the SRN indicated a Hill slope (nH) of approximately 2 for all agonists except GABA and guanidinopropionic acid (nH greater than 2), two compounds known to be actively accumulated by cellular GABA uptake processes. Nipecotic acid, guvacine, and L-alpha, beta-diaminopropionic acid, blockers of GABA uptake processes, had essentially no effect by themselves on the SRN membrane input conductance at concentrations up to 5 mM, however, they potentiated the effects of sub-maximal concentrations of GABA and decreased the steepness of the log concentration-conductance curve, and consequently nH, for GABA. The effects of muscimol, however, were not affected. When the influence of uptake processes was considered, it appeared that all agonists tested acted by the same cooperative mechanism which required at least two molecules of agonist to activate a receptor-ionophore unit.

Animals↗
PubMed1981

Specific cerebrovascular localization of glutamate decarboxylase activity.

Glutamate decarboxylase (GAD) activity and GABA levels, determined with a [3H]muscimol radioreceptor assay, were found to be significantly higher in cerebral blood vessels from the piaarachnoid membrane as compared to extracranial vessels (aorta, mesenteric and femoral arteries, and vena cava). A cerebrovascular localization for GABA and GAD is consistent with earlier studies suggesting that an indigenous GABA system is involved in cerebral vascular function.

Animals↗
PubMed1980

GABA receptors in bovine cerebral blood vessels: binding studies with [3H]muscimol.

[3H]Muscimol, a potent GABA agonist used to label GABA receptor sites in brain and invertebrate striated muscle, was found to bind specifically to sites in a crude membrane fraction prepared from bovine cerebral blood vessels. Specific [3H]muscimol binding was saturable of high affinity (Kd = 41 nM), and was selectively inhibited by GABA, specific GABA agonists, and the antagonist bicuculline with potencies similar to what has been found for GABA receptors in mammalian brain. GABA and several GABA agonists including muscimol have been reported to dilate isolated cerebral arteries, but not peripheral blood vessels. The pharmacology of the [3H]muscimol binding site correlated well with that of the vasodilatory response. No significant specific [3H]muscimol binding was detected in aorta and mesenteric arteries. The characteristics of the cerebrovascular muscimol binding site thus are indicative of a physiologically relevant GABA receptor associated with cerebral blood vessels. These findings suggest a direct role for GABA in cerebral vascular function.

Animals↗
PubMed1979

Pharmacological characterization of GABA receptors mediating vasodilation of verebral arteries in vitro.

GABA (gamma-aminobutyric acid) produced a dose-dependent dilation of isolated cat and dog cerebral artery segments which had been given an active, tonic contraction by either prostaglandin F2 alpha or serotonin. No effect of GABA on extracranial blood vessels was observed. The GABA-induced dilation could be blocked in a dose-dependent manner by either bicuculline or picrotoxin. The latter agent appeared to act as a competitive antagonist. GABA agonists muscimol, imidazoleacetic acid, delta-aminovaleric acid, (+/-)gamma-amino-beta-hydroxybutyric acid, and beta-alanine also relaxed actively contracted cerebral arteries dose-dependently. The relative potency of these agonists was consistent with that established for GABA receptors on neurons and invertebrate striated muscle. GABA was also tested on two human cerebral arteries and found to cause a small dilation. The results support the existence of a cerebrovascular GABA receptor which may mediate an interaction between GABA and the cerebral circulatory system.

Animals↗
PubMed1970

Studies on the pathogenesis of fever. XX. Suppression and regeneration of pyrogen-producing capacity of exudate granulocytes.

Suppression of the pyrogen-producing capacity of exudate granulocytes results from incubation of the cells in plasma, serum, or Ringer's solution. When transferred in this state and incubated in isotonic NaCl, the cells release much less pyrogen than untreated exudate cells. The suppressive effect is reversible and appears to involve the cellular uptake of calcium ions. In contrast, regeneration of pyrogen-producing capacity in depleted exudate cells occurs only when the cells are incubated in serum. The process resembles activation and requires the cellular synthesis of protein.

Blood↗