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H J Granger

Publications and source records attributed to H J Granger.

At least 19 recordsLinked to original sources
PubMed1995

Interaction of neutrophils and endothelium in isolated coronary venules and arterioles.

This study reports measurements of porcine neutrophil dynamics in isolated microvessels. Porcine coronary venules and arterioles were isolated, cannulated, and perfused with fluorescently labeled neutrophils at a series of flow velocities. In venules (62.50 +/- 5.41 microns diam) under control conditions, rolling neutrophils were often observed at intraluminal flow velocities ranging from 600 to 6,000 microns/s, and the rolling fraction varied inversely as a function of flow velocity. There was no significant adherence under the control conditions at any of the various flow velocities. Pretreatment of the neutrophils with human recombinant complement 5a (C5a, 10(-8) M) increased adherence at low flow velocities but did not alter the rolling fraction. In contrast to venules, rolling neutrophils were not observed in arterioles (58.80 +/- 5.6 microns diam). Furthermore, neutrophils that were pretreated with C5a did not adhere to the arteriolar endothelium even at low flow velocities. We suggest that 1) isolated microvessels perfused with fluorescently labeled neutrophils are suitable models for the study of the interaction between neutrophils and the microvascular endothelium, 2) shear force plays an important role in neutrophil rolling in coronary venules but is not the major factor that prevents neutrophil rolling and adherence in arterioles, and 3) C5a causes neutrophil adherence in venules but not in arterioles, indicating that different mechanisms underlie the interaction between neutrophils and endothelium in venules and arterioles.

Animals↗
PubMed1995

Oxidative injury of coronary venular endothelial cells depletes intracellular glutathione and induces HSP 70 mRNA.

Vascular endothelium is one of the first tissues exposed to reactive oxygen species produced during myocardial ischemia-reperfusion. Bovine coronary venular endothelial cells (CVEC) were evaluated for intracellular glutathione (GSH) levels and heat shock protein 70 (HSP 70) mRNA and protein during in vitro oxidative stress. CVEC were incubated with 0.01875 U/ml xanthine oxidase (XO) and 0.5 mM hypoxanthine (HX) for 30 min and then allowed to recover for 0, 1, 2, or 3 h. Relative GSH levels were determined by evaluation of monochlorobimane fluorescence. GSH fluorescence was significantly lower in CVEC treated with XO+HX for 30 min than in controls. GSH fluorescence was also decreased in heat-shocked CVEC. After oxidative stress, GSH levels were higher than in controls at 1 h, but by 2 or 3 h after treatment, GSH fluorescence fell below control values. HSP 70 mRNA was induced in CVEC by a 30-min treatment with XO+HX exposure. These data suggest that CVEC respond to oxidative stress by reducing intracellular GSH levels and inducing HSP 70 mRNA, although significant increases in HSP 70 protein were not detected at the time points tested.

Animals↗
PubMed1994

Nuclear accumulation of exogenous basic fibroblast growth factor in endothelial, fibroblast, and myoblast cell lines results in diverse biological responses.

During studies comparing 125I-bFGF internalization between endothelial cells and other cell types, we found, unexpectedly, internalization and nuclear translocation of exogenously added 125I-bFGF in two cell lines: Chinese hamster ovary cells (CHO) and rat L6 myoblasts. These cell lines were previously reported to be devoid of FGF receptors. Furthermore, CHO cells showed a weak mitogenic response to added bFGF, while L6 cells were mitogenically unresponsive. By comparison, coronary venular endothelial cells (CVEC), BALB/c 3T3 fibroblasts, and BHK-21 cells, demonstrated internalization and nuclear translocation of added 125I-bFGF, and mitogenic responsiveness to the growth factor. Insulin alone stimulated DNA synthesis in all cell types, yet augmented bFGF-dependent DNA synthesis only in CVEC, 3T3, and BHK. All five cell types expressed FGF receptors as assessed by covalent crosslinking with 125I-bFGF and immunoblotting with anti-FGF receptor antibodies. Differing rates of cytoplasmic and nuclear accumulation of 125I-bFGF and partial inhibition of internalization by pretreatment of CVEC with chlorate support a recent model that bFGF can internalize by two mechanisms. Insulin did not significantly affect 125I-bFGF internalization or metabolism in any cell type. bFGF treatment resulted in weak inhibition of RNA synthesis in L6 cells. bFGF appears firmly bound to the nuclear matrix as little nuclear-bound 125I-bFGF in CVEC is released by DNAse I or RNAse A digestion, while washes with 0.5 M NaCl result in partial release. Nuclear bFGF may thus be involved in regulation of nuclear events (e.g., gene transcription and/or DNA replication).

3T3 Cells↗
PubMed1994

Tyrosine kinase inhibitors impair fibroblast growth factor signaling in coronary endothelial cells.

We examined the effect of various tyrosine kinase inhibitors on basic fibroblast growth factor (bFGF)-induced cell signaling and DNA synthesis in coronary venular endothelial cells (CVEC). Two tyrosine kinase inhibitors, genistein and methyl 2,5-dihydroxycinnamate, showed reversible, dose-dependent inhibition of bFGF-stimulated DNA synthesis in CVEC with half-maximal inhibitory concentrations of 12 and 3 microM, respectively. Both compounds exhibited preferential inhibition of bFGF vs. serum-induced DNA synthesis. bFGF stimulated increased tyrosine phosphorylation of CVEC cellular proteins, including the FGF receptor, which were visible within 1 min of treatment. Concomitant with their effect on DNA synthesis, both compounds exhibited dose-dependent inhibition of tyrosine phosphorylation of intracellular substrates induced by bFGF. A 2-h pretreatment of quiescent CVEC with genistein blocked nuclear translocation but not cytoplasmic internalization of bFGF, whereas the same treatment with methyl 2,5-dihydroxycinnamate inhibited both processes. These results suggest that activation of bFGF receptor tyrosine kinase activity plays a role in nuclear translocation of bFGF and initiation of DNA synthesis in endothelial cells.

Animals↗
PubMed1994

Nitric oxide mediates angiogenesis in vivo and endothelial cell growth and migration in vitro promoted by substance P.

We evaluated the effects of nitric oxide (NO) generators and endogenous production of NO elicited by substance P (SP) in the angiogenesis process. Angiogenesis was monitored in the rabbit cornea in vivo and in vitro by measuring the growth and migration of endothelial cells isolated from coronary postcapillary venules. The angiogenesis promoted in the rabbit cornea by [Sar9]-SP-sulfone, a stable and selective agonist for the tachykinin NK1 receptor, and by prostaglandin E1 (PGE1), was potentiated by sodium nitroprusside (SNP). Conversely, the NO synthase inhibitor N omega-nitro-L-arginine methyl ester (L-NAME), given systemically, inhibited angiogenesis elicited by [Sar9]-SP-sulfone and by PGE1. Endothelial cells exposed to SNP exhibited an increase in thymidine incorporation and in total cell number. Exposure of the cells to NO generating drugs, such as SNP, isosorbide dinitrate, and glyceryl trinitrate, produced a dose-dependent increase in endothelial cell migration. Capillary endothelial cell proliferation and migration produced by SP were abolished by pretreatment with the NO synthase inhibitors N omega-mono-methyl-L-arginine (L-NMMA), N omega-nitro-L-arginine (L-NNA), and L-NAME. Exposure of the cells to SP activated the calcium-dependent NO synthase. Angiogenesis and endothelial cell growth and migration induced by basic fibroblast growth factor were not affected by NO synthase inhibitors. These data indicate that NO production induced by vasoactive agents, such as SP, functions as an autocrine regulator of the microvascular events necessary for neovascularization and mediates angiogenesis.

Amino Acid Oxidoreductases↗
PubMed1993

Substance P increases cyclic GMP levels on coronary postcapillary venular endothelial cells.

The vasodilating effect of substance P (SP) at the microvascular level is endothelium-dependent. In the present study we evaluated whether SP activates nitric oxide (NO) production by venular endothelial cell. We evaluated NO activation by measuring cyclic GMP levels in cultured endothelial cells isolated from coronary postcapillary venules of bovine origin (CVEC). Our results indicate that 5 min exposure of CVEC to 10 nM SP doubled basal cyclic GMP levels. Cell treatment with the NO synthase inhibitor L-NMMA reduced the basal levels of cyclic GMP and abolished the effect of SP but did not modify the increase in cyclic GMP in response to exogenous NO. These data indicate that a) microvascular endothelium responds in an autocrine fashion to NO with increased cyclic GMP levels, b) SP activates cyclic GMP pathway through NO production.

Animals↗
PubMed1993

Microvascular pressure and albumin extravasation after leukocyte activation in hamster cheek pouch.

The effects of leukotriene B4 (LTB4) and N-formyl-methionyl-leucylphenylalanine (FMLP) on transmicrovascular exchange of fluorescein isothiocyanate (FITC)-labeled serum albumin and dextran (molecular mass, 150,000 Da) were evaluated in hamster cheek pouch utilizing measurements of microvascular pressure and global efflux of the macromolecular markers into the tissue suffusate. Exposure of the suffused pouch to 1.0 microM LTB4 failed to alter microvascular pressure from its control level. The microvascular clearance of FITC-albumin rose to a peak value of 1.7 times the control value at a LTB4 concentration of 1.0 microM; the rate of albumin extravasation did not change from the normal level at a concentration of 0.1 microM. The extravasation rate of FITC-dextran was elevated with both doses of LTB4; the leukocyte chemotactic agent elicited 2.4- and 9.7-fold increments in peak clearance of dextran at concentrations of 0.1 and 1.0 microM, respectively. FMLP elicited a twofold increase in venular and terminal arteriolar pressures at a concentration of 1 microM; at the same concentration, the albumin clearance rose 3.5-fold. The results suggest that albumin transport remains near the normal level after LTB4 elicits massive migration of leukocytes across the venular membrane. By contrast, albumin transport is greatly accelerated following exposure to the chemotactic peptide FMLP; ultrastructural and physiological evidence suggests that the leakage of albumin is augmented by increases in microvascular permeability and filtration pressure. The results also reinforce previous ultrastructural observations from our laboratory indicating that diapedesis per se is not a cause of microvascular hyperpermeability in inflammatory reactions.

Animals↗
PubMed1993

Histamine increases venular permeability via a phospholipase C-NO synthase-guanylate cyclase cascade.

In this study, we hypothesized that histaminergic increases in venular permeability result from a cascade triggered by activation of phospholipase C (PLC), inducing the synthesis of nitric oxide (NO) and activating guanylate cyclase. The apparent permeability coefficient to albumin (Pa) was measured in isolated porcine coronary venules subjected to constant flow and hydrostatic and oncotic pressures. Histamine (2.5, 5, and 10 microM) transiently and progressively increased Pa. The PLC inhibitor 2-nitro-4-carboxyphenyl N,N-diphenylcarbamate (NCDC; 100 microM) decreased baseline permeability and abolished the effect of histamine. The NO synthase inhibitor NG-monomethyl-L-arginine (L-NMMA; 10 microM) and the guanylate cyclase inhibitor 6-anilinoquinoline-5,8-quinone (LY 83583; 10 microM) also blocked the histamine-induced hyperpermeability. L-Arginine (3 mM) reversed the inhibition by L-NMMA. NG-monomethyl-D-arginine did not influence the effect of histamine. Furthermore, sodium nitroprusside (10 microM) augmented Pa by two- to threefold; this effect was blocked in the presence of LY 83583 but not altered in the presence of NCDC. The results suggest that histamine increases coronary venular permeability by a direct action on the venular endothelial cells through a PLC-NO synthase-guanylate cyclase-signaling cascade.

Amino Acid Oxidoreductases↗
PubMed1993

Permeability to albumin in isolated coronary venules.

This study reports measurements of albumin permeability in isolated coronary venules. The isolated microvessel technique allows the quantification of transmural exchange of macromolecules under tightly controlled physical and chemical conditions. Transvenular exchange of albumin was studied in isolated coronary venules during alterations in filtration rate caused by changes in intravascular pressure. The apparent permeability coefficient of albumin (Pa) at an intraluminal pressure of 11 cmH2O was 3.92 +/- 0.43 x 10(-6) cm/s. Elevating intraluminal pressure to 16 and 21 cmH2O increased Pa to 5.13 +/- 0.57 x 10(-6) and 6.78 +/- 0.66 x 10(-6) cm/s, respectively. Calculation of the true diffusive permeability coefficient of albumin (Pd) at zero filtration rate was 1.54 x 10(-6) cm/s. The product of hydraulic conductance (Lp) and (1 - sigma), where sigma is the solute reflection coefficient, was 3.25 x 10(-7) cm.s-1 x cmH2O-1. At a net filtration pressure of 4-5 cmH2O, diffusion accounts for > 60% of total albumin transport across the venular wall. Transmural albumin flux is very sensitive to filtration rate, rising 6.7% for each cmH2O elevation of net filtration pressure. At 11 cmH2O net filtration pressure, convection accounts for nearly 70% of net albumin extravasation from the venular lumen. We suggest that the isolated coronary venule is a suitable preparation for the study of solute exchange in the heart.

Animals↗
PubMed1993

Enhanced myogenic activation in skeletal muscle arterioles from spontaneously hypertensive rats.

The purpose of this study was to determine whether the vascular myogenic response is enhanced in hypertension. Experiments were conducted in the intact cremaster muscle microcirculation as well as in isolated arterioles of hypertensive (SHR) and normotensive (WKY) rats. Increasing venous pressure in vivo by approximately 5 mmHg had no effect on normotensive first- (1A) or third-order arteriolar (3A) diameters; in contrast, hypertensive 1A diameter decreased 4% (89 +/- 2 to 85 +/- 3 microns) with an 8% decrease in 3A (24 +/- 2 to 22 +/- 2 microns). To further examine this enhanced constriction to elevated intravascular pressure in SHR, diameter was monitored in isolated 1A during step increases and decreases in intraluminal pressure. Normotensive arterioles displayed myogenic responses between pressures of 50 and 170 cmH2O; in contrast, hypertensive arterioles demonstrated myogenic responses over an extended pressure range (50-210 cmH2O). In addition, the change in diameter for each step change in pressure was greater in the arterioles from SHR, indicating an increased myogenic responsiveness. The myogenic reactions were unaffected by alpha-receptor blockade with phentolamine (10(-6) M), indicating that adrenergic hypersensitivity was not involved in the enhanced response to stretch. Morphometric analysis of the vascular wall revealed no differences in wall thickness, cross-sectional wall area, or wall-to-lumen ratio between normotensive and hypertensive rats. The length-tension relationships for normotensive and hypertensive rats demonstrated that peak active tension occurred at nearly the same vascular smooth muscle length. In addition, SHR arterioles were capable of maintaining higher levels of active tension that WKY arterioles, indicating an altered length-tension curve in chronic arterial hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Oxygen radicals, enzymes, and fluid transport through pericardial interstitium.

The interstitium is the final link in the transportation of nutrients from the bloodstream to the individual cells of an organism. To assess interstitial fluid transport in normal and inflamed tissue, the hydration (H, ml H2O/g dry wt) and hydraulic conductivity (Kp, 10(-8) cm2.s-1.cmH2O-1) of bovine pericardial stroma were determined. The effect of enzymes and neutrophil-derived products of inflammation on the properties of the interstitial model were determined. Samples of the pericardium were exposed separately to trypsin, elastase, hyaluronidase, collagenase, superoxide radicals, and hydrogen peroxide. After exposure, the tissues were washed repeatedly in physiological saline and equilibrated in transport chambers heated to 37 degrees C and pressurized to 50 cmH2O. Fluid flow across the tissues was monitored. A section of tissue was removed and weighed. The tissue section was subsequently dried and reweighed. Tissue thickness, H, and Kp were calculated. H and Kp of the control tissues were 2.82 +/- 0.04 and 1.71 +/- 0.07, respectively. Hydration was significantly increased (22-38%) by exposure to trypsin, elastase, collagenase, and superoxide radicals. Kp increased significantly (30-1055%) in the groups treated with trypsin, hyaluronidase, collagenase, and superoxide radicals. The inflammatory mediators generally increased the hydration and/or the hydraulic conductivity of the model. These results indicate that neutrophil-derived products could be involved in the development of interstitial edema during the inflammatory process.

Animals↗
PubMed1992

Internalized basic fibroblast growth factor translocates to nuclei of venular endothelial cells.

To begin to understand the molecular mechanisms by which basic fibroblast growth factor (bFGF) stimulates proliferation of coronary venular endothelial cells (CVEC), we have characterized the kinetic interactions of bFGF with various binding sites on CVEC and determined the kinetics of nuclear translocation of bFGF. We report that bFGF rapidly binds to its receptor and is immediately internalized at 37 degrees C with a half-time for receptor binding of 0.9 min. After internalization bFGF is processed by two kinetically and biochemically distinguishable pathways. Up to 40-50% of total internalized bFGF is translocated to the nuclei of serum-starved, quiescent cells at early time points (0-2 h). This proportion declines to less than or equal to 20% by 24 h. Cytoplasmic accumulation continued to increase for up to 24 h. Nuclear-bound 125I-labeled bFGF consisted primarily of the intact 18-kDa species with small amounts of a 16-kDa degradation fragment. Nuclear-bound 125I-labeled bFGF showed little evidence of degradation even after 24 h, whereas cytoplasmic 125I-labeled bFGF showed increased degradation to smaller fragments with time. Nuclear-binding of bFGF reached equilibrium by 8 h, just before initiation of DNA synthesis, which began 9-12 h after growth factor addition. These results suggest that nuclear-bound bFGF may function in triggering division (proliferation) of CVEC subsequent to binding of the growth factor to cell surface receptors.

Animals↗
PubMed1992

Flow modulates coronary venular permeability by a nitric oxide-related mechanism.

This study demonstrates that flow velocity modulates coronary venular permeability to albumin. Apparent permeability coefficients of albumin (Pa) were measured in isolated cannulated coronary venules ranging from 30 to 70 microns in diameter. Hydrostatic and oncotic pressures were controlled while the intraluminal flow velocity was varied. Pa at an intraluminal hydrostatic pressure of 12 cmH2O and a flow velocity of 7 mm/s was 4.01 +/- 0.53 x 10(-6) cm/s. Increasing flow velocity to 10 and 13 mm/s augmented the permeability by 33 +/- 14 and 48 +/- 14%, respectively. The nitric oxide synthase inhibitor, NG-monomethyl-L-arginine (L-NMMA) (10(-5) M), decreased baseline Pa and abolished the flow-induced permeability changes. Administration of L-arginine (3 x 10(-3) M), a physiological precursor of nitric oxide which reverses the effect of L-NMMA, restored the relationship between flow and permeability. From these results we conclude that 1) flow velocity should be considered as a physical force that potentially modulates permeability of venular exchange vessels in the heart and 2) flow modulates coronary venular permeability via the production of nitric oxide.

Animals↗
PubMed1992

[The effect of vasoactive factors on the growth of of coronary endothelial cells].

The aim of this study was to evaluate the effect of adenosine and bradykinin on endothelial cell growth at capillary level. DNA synthesis was measured in subconfluent capillary endothelial cells obtained from coronary venules (CVEC) after exposure to adenosine or bradykinin. Our results indicate that adenosine and bradykinin induced a dose-dependent proliferation of CVEC. Maximal effect was observed at the dose 100 microM concentration for adenosine and 0.1 microM concentration for bradykinin.

Adenosine↗
PubMed1991

Reactive oxygen metabolites inhibit spontaneous lymphatic contractions.

The effects of oxygen-derived free radicals on the contractile activity of the mesenteric collecting lymphatics were evaluated in the anesthetized rat. Lymphatic contractions were monitored before, during and after the application of oxyradicals. Contraction frequency (F), stroke volume (SV), ejection fraction (EF), contraction propagation (PC), and lymph pump flow (LPF) were determined from the lymphatic diameter tracings. Oxyradicals were generated using hypoxanthine and xanthine oxidase. Exposure to oxyradicals inhibited the lymphatic pumping mechanism: 1) F fell from 15.5 +/- 0.8 to 0.8 +/- 0.7 beats/min; 2) EF went from 0.44 +/- 0.02 to 0.08 +/- 0.04; 3) PC dropped from 92 +/- 2 to 56 +/- 8%; and 4) LPF fell precipitously from 41.0 +/- 5.2 to 0.7 +/- 0.4 nl/min. The effects of the oxyradicals were attenuated by superoxide dismutase, implicating superoxide anion as one of the predominant causative agents. We conclude that oxyradicals significantly inhibit the lymph pump and that this inhibition could be a factor contributing to the formation of interstitial edema during inflammation.

Animals↗
PubMed1991

Lymph flow transients following elevation of venous pressure in the dog hindpaw.

Lymph flow transients were studied in a dog paw preparation when venous pressure was elevated by 15 and 25 mmHg. The lymph flow transients showed a very rapid initial increase which then declined to a steady-state value that was one-half the peak lymph flow response for both pressure changes. Lymph flow increased in the initial 5.3 minutes following venous pressure elevation to 10.4 +/- 2.0 and 18.1 +/- 4.5 times the normal lymph flow (mean +/- standard deviation) for the 15 and 25 mmHg increases in venous pressure, respectively. However, approximately 9 minutes after attaining the maximal flow rate, the lymph flow declined to only 5.5 +/- 0.7 and 9.8 +/- 1.8 times the control values. These data demonstrate another condition in which lymph flow is not maintained at the maximal capability. Possible mechanisms causing the observed biphasic lymph flow response to capillary pressure elevation are: 1) changes in Starling forces oppose an increase in capillary pressure; 2) the rate of change in tissue fluid pressure affects lymph flow to a greater extent than does the absolute change in tissue fluid pressure; or, 3) the lymphatics empty upon elevation and refill as the capillaries filter.

Animals↗