Intracellular mechanisms involved in the responses of cerebrovascular smooth-muscle cells to hemoglobin

1994 ◽  
Vol 80 (2) ◽  
pp. 261-268 ◽  
Author(s):  
Bozena A. M. Vollrath ◽  
Bryce K. A. Weir ◽  
R. Loch Macdonald ◽  
David A. Cook

✓ An investigation was undertaken of the mechanism by which oxyhemoglobin and its analog methemoglobin might cause cerebrovascular spasm. The effect of these compounds on the levels of intracellular inositol triphosphate and calcium in cultured primate cerebrovascular smooth-muscle cells and the contractile action of oxyhemoglobin on isolated rings of primate cerebral arteries were also examined. Oxyhemoglobin, but not methemoglobin, produces a transient but highly significant increase in the intracellular levels of inositol triphosphate. Intracellular calcium levels in these cells are increased by thrombin, aluminum tetrafluoride, and oxyhemoglobin, and the sustained elevation in intracellular calcium is prevented by ethyleneglycol tetra-acetic acid and the phospholipase C inhibitor neomycin. Removal of the oxyhemoglobin after as long as 48 hours' incubation with this compound allowed cells to rapidly reduce their intracellular calcium levels to near normal. Oxyhemoglobin produced contractions of isolated rings of both normal and spastic cerebral arteries, although the response of spastic vessels was significantly smaller. This effect was inhibited by neomycin. The addition of neomycin relaxed arteries that were contracted with oxyhemoglobin, 5-hydroxytryptamine, or potassium chloride. It is thus likely that activation of phospholipase C is a critical step in the development of vasospasm, but the transient nature of the response to inositol triphosphate suggests that the sustained contraction may arise from other phospholipase C-dependent mechanisms.

1995 ◽  
Vol 82 (2) ◽  
pp. 244-249 ◽  
Author(s):  
Kazuhiko Nagatani ◽  
Jeffery E. Masciopinto ◽  
Peter B. Letarte ◽  
Robert A. Haworth ◽  
Thomas A. Duff

✓ Cerebral arteries in spasm have been found to contain low levels of adenosine triphosphate (ATP), and it has been postulated that this change in levels results from hypoxia produced by arterial encasement in clotted material. This study was undertaken to determine whether any of four blood-derived agents, ferrous hemoglobin, methemoglobin, hemin, or bilirubin, is capable of reducing energy levels in cerebral artery smooth-muscle cells. Twenty-four-hour exposure of cultured canine basilar artery cells to ferrous hemoglobin and bilirubin led to a significant decline in ATP levels (to 8.9 nmol/mg protein and 2.8 nmol/mg protein, respectively) versus control (16.6 nmol/mg protein); methemoglobin and hemin showed no effect. Bilirubin but not hemoglobin was found to interfere with electron transport and with creatine phosphokinase activity in intact cells; however, bilirubin showed no inhibitory effect on this enzyme in cell-free conditions. The findings indicate that hemoglobin and bilirubin may be responsible for diminished energy levels in cerebral arteries. These observations also suggest that bilirubin may exert its effect on ATP by impairing mitochondrial function.


1991 ◽  
Vol 69 (3) ◽  
pp. 393-399 ◽  
Author(s):  
Y. Wang ◽  
K. G. Baimbridge ◽  
D. A. Mathers

Smooth muscle cells were dissociated from conducting cerebral arteries of adult rats and maintained in culture for 2–4 days. The calcium-sensitive fluorescent probe, fura-2, was used to study the effect of the vasoconstrictor serotonin (5-HT) on the level of free intracellular Ca2+ in these cells. The baseline level of free intracellular calcium was 39 ± 3.6 nM. In 74 out of 110 cells, 5-HT application transiently increased the free Ca2+ content. This effect was dose-dependent and was suppressed by nanomolar concentrations of the 5-HT2 receptor antagonist, ketanserin. The 5-HT induced rise in free intracellular calcium was not prevented by the presence of Co2+, La3+, or nifedipine, blockers of voltage-sensitive calcium channels. These results indicate that 5-HT mobilizes intracellular Ca2+ in cultured smooth muscle cells derived from the rat cerebrovasculature. The mobilization of intracellular Ca2+ appears to be triggered by a 5-HT2 type receptor, although further pharmacological experiments are required to verify this hypothesis.Key words: serotonin, smooth muscle, cerebral artery, intracellular calcium, fura-2.


1983 ◽  
Vol 58 (6) ◽  
pp. 843-850 ◽  
Author(s):  
Tetsumori Yamashima ◽  
Shinjiro Yamamoto

✓ Pathological changes of the cerebral arteries were studied in 30 dogs after subarachnoid injections of saline, fresh autologous blood, epinephrine, blood plus epinephrine, norepinephrine, or blood plus norepinephrine. Macroscopically, the circle of Willis was maximally dilated after the injection of epinephrine and was constricted following administration of blood plus epinephrine. Microscopically, neither saline nor blood produced abnormalities, except for minor changes of the adventitia in the latter. Epinephrine produced frank necrosis of smooth-muscle cells, which was subsequently replaced by fibrosis in the media of larger subarachnoid arteries, and the leakage of necrotic material from the infarcted hypothalamus contributed to these lesions. Blood plus epinephrine produced marked changes in the internal elastic lamina and tortuosities of the nuclei of smooth-muscle cells, while norepinephrine and blood plus norepinephrine produced only minor changes. Previously reported findings of morphological changes due to vasospasm after subarachnoid hemorrhage were confirmed experimentally, but such changes were found only after application of epinephrine. It is suggested that epinephrine produced the most severe vasospasm among the five substances tested.


1987 ◽  
Vol 67 (4) ◽  
pp. 565-572 ◽  
Author(s):  
Tadayoshi Nakagomi ◽  
Neal F. Kassell ◽  
Tomio Sasaki ◽  
Shigeru Fujiwara ◽  
R. Michael Lehman ◽  
...  

✓ The purpose of this experiment was to evaluate the effect of hypoxia on the in vitro contractile responses of canine basilar artery to KCl, prostaglandin (PG) F2α, and hemoglobin. Hypoxia was induced by changing the bubbling gas mixture in the chamber from 95% O2/5% CO2 to 95% N2/5% CO2. Hypoxia augmented the contractile response developed at 95% O2 to 25 mM and 50 mM KCl, 3 × 10−7 M and 10−5 M PGF2α, and 10−6 M hemoglobin. No significant alteration of the hypoxic augmentation in any preparation exposed to 25 mM KCl, 3 × 10−7 M PGF2α, or 10−6 M hemoglobin was observed with guanethidine (10−5 M), prazosin (10−5 M), methysergide (10−5 M), or diphenhydramine (10−5 M). Endothelial denudation did not affect hypoxic augmentation. Hypoxia did not cause any alteration of the contractile response to 10−6 M PGF2α in Ca++-free media. Pretreatment with a calcium channel blocker, nicardipine, significantly inhibited the hypoxic potentiation of the contractile response to 25 mM KCl, 3 × 10−7 M PGF2α, and 10−6 M hemoglobin. These results suggest that hypoxia augments the contractile response to these agonists by a direct action on the smooth-muscle cells, facilitating the transmembrane influx of extracellular calcium. Hypoxia of smooth-muscle cells in the major cerebral arteries might be involved in the pathogenesis of vasospasm.


2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Joseph A. Jude ◽  
Mythili Dileepan ◽  
Reynold A. Panettieri ◽  
Timothy F. Walseth ◽  
Mathur S. Kannan

CD38 is a transmembrane glycoprotein expressed in airway smooth muscle cells. The enzymatic activity of CD38 generates cyclic ADP-ribose from β-NAD. Cyclic ADP-ribose mobilizes intracellular calcium during activation of airway smooth muscle cells by G-protein-coupled receptors through activation of ryanodine receptor channels in the sarcoplasmic reticulum. Inflammatory cytokines that are implicated in asthma upregulate CD38 expression and increase the calcium responses to contractile agonists in airway smooth muscle cells. The augmented intracellular calcium responses following cytokine exposure of airway smooth muscle cells are inhibited by an antagonist of cyclic ADP-ribose. Airway smooth muscle cells from CD38 knockout mice exhibit attenuated intracellular calcium responses to agonists, and these mice have reduced airway response to inhaled methacholine. CD38 also contributes to airway hyperresponsiveness as shown in mouse models of allergen or cytokine-induced inflammatory airway disease. In airway smooth muscle cells obtained from asthmatics, the cytokine-induced CD38 expression is significantly enhanced compared to expression in cells from nonasthmatics. This differential induction of CD38 expression in asthmatic airway smooth muscle cells stems from increased activation of MAP kinases and transcription through NF-κB, and altered post-transcriptional regulation through microRNAs. We propose that increased capacity for CD38 signaling in airway smooth muscle in asthma contributes to airway hyperresponsiveness.


2011 ◽  
Vol 52 (3) ◽  
pp. 185-193 ◽  
Author(s):  
Tomofumi Tanaka ◽  
Kenichi Ikeda ◽  
Yumiko Yamamoto ◽  
Haruko Iida ◽  
Hironobu Kikuchi ◽  
...  

2003 ◽  
Vol 285 (3) ◽  
pp. H1347-H1355 ◽  
Author(s):  
Jin Han ◽  
Nari Kim ◽  
Hyun Joo ◽  
Euiyong Kim

Although ketamine and Ca2+-activated K+ (KCa) channels have been implicated in the contractile activity regulation of cerebral arteries, no studies have addressed the specific interactions between ketamine and the KCa channels in cerebral arteries. The purpose of this study was to examine the direct effects of ketamine on KCa channel activities using the patch-clamp technique in single-cell preparations of rabbit middle cerebral arterial smooth muscle. We tested the hypothesis that ketamine modulates the KCa channel activity of the cerebral arterial smooth muscle cells of the rabbit. Vascular myocytes were isolated from rabbit middle cerebral arteries using enzymatic dissociation. Single KCa channel activities of smooth muscle cells from rabbit cerebral arteries were recorded using the patch-clamp technique. In the inside-out patches, ketamine in the micromolar range inhibited channel activity with a half-maximal inhibition of the ketamine conentration value of 83.8 ± 12.9 μM. The Hill coefficient was 1.2 ± 0.3. The slope conductance of the current-voltage relationship was 320.1 ± 2.0 pS between 0 and +60 mV in the presence of ketamine and symmetrical 145 mM K+. Ketamine had little effect on either the voltage-dependency or open- and closed-time histograms of KCa channel. The present study clearly demonstrates that ketamine inhibits KCa channel activities in rabbit middle cerebral arterial smooth muscle cells. This inhibition of KCa channels may represent a mechanism for ketamine-induced cerebral vasoconstriction.


2002 ◽  
Vol 283 (6) ◽  
pp. L1271-L1279 ◽  
Author(s):  
Albrecht Bergner ◽  
Michael J. Sanderson

In airway smooth muscle cells (SMCs) from mouse lung slices, ≥10 μM ATP induced Ca2+oscillations that were accompanied by airway contraction. After ∼1 min, the Ca2+oscillations subsided and the airway relaxed. By contrast, ≥0.5 μM adenosine 5′- O-(3-thiotriphosphate) (nonhydrolyzable) induced Ca2+oscillations in the SMCs and an associated airway contraction that persisted for >2 min. Adenosine 5′- O-(3-thiotriphosphate)-induced Ca2+oscillations occurred in the absence of external Ca2+but were abolished by the phospholipase C inhibitor U-73122 and the inositol 1,4,5-trisphosphate receptor inhibitor xestospongin. Adenosine, AMP, and α,β-methylene ATP had no effect on airway caliber, and the magnitude of the contractile response induced by a variety of nucleotides could be ranked in the following order: ATP = UTP > ADP. These results suggest that the SMC response to ATP is impaired by ATP hydrolysis and mediated via P2Y2or P2Y4receptors, activating phospholipase C to release Ca2+via the inositol 1,4,5-trisphosphate receptor. We conclude that ATP can serve as a spasmogen of airway SMCs and that Ca2+oscillations in SMCs are required to sustain airway contraction.


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