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Biomedical subjects

C N Gillis

Publications and source records attributed to C N Gillis.

At least 19 recordsLinked to original sources
PubMed1992

Ginsenosides protect pulmonary vascular endothelium against free radical-induced injury.

We studied the actions of saponin (ginsenosides) from Panax ginseng on free radical-induced pulmonary endothelial injury which is manifest as reversal of the normal vasodilator response to acetylcholine in perfused, vasoconstricted lungs. 50 or 200 micrograms/ml ginsenosides prevented this injury response and also reduced the pulmonary edema which follows free radical injury but did not alter the normal ACh-induced vasodilation in intact lungs. In control perfused lungs preconstricted with U46619, the ginsenoside mixture or purified ginsenosides Rb1 and Rg1 caused vasodilatation. This effect was eliminated by 100 microM nitro-L-arginine, an inhibitor of nitric oxide synthase. In cultured bovine aortic endothelial cells, ginsenosides (10 micrograms/ml) stimulated the conversion of [14C]-L-arginine to [14C]-L-citrulline. These data indicate that GS may cause vasorelaxation and prevent manifestations of oxygen free radical injury by promoting release of nitric oxide.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1992

Enhanced photorelaxation in aorta, pulmonary artery and corpus cavernosum produced by BAY K 8644 or N-nitro-L-arginine.

Segments of endothelium-denuded aorta, pulmonary arterial rings and strips of corpus cavernosum from rabbits were superfused with Krebs medium. Photorelaxation elicited by ultraviolet light (366 nm) was significantly enhanced by either BAY K 8644 (20 nM) or N-nitro-L-arginine (100 and 500 microM) and was associated with increased cyclic GMP. This action of both drugs was greater in pulmonary artery than aorta and corpus cavernosum and persisted in vascular rings for 90 min after drug removal. The effect was significantly attenuated by hemoglobin (10 microM) but was unaltered by superoxide dismutase (30 u/ml). The mechanism of such photosensitization is presently unclear.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1992

Rapid reversal of angiotensin converting enzyme inhibition by lisinopril in the perfused rabbit lung.

Lisinopril is a potent competitive inhibitor of purified rabbit lung ACE (dissociation t1/2 = 105 min). To examine reversibility of binding and ACE functional activity in situ, the single-pass extraction (E) of an 125I-lisinopril analogue (351A) and the hydrolysis of an ACE substrate, benz-phe-ala-pro (BPAP) were studied. Lungs were perfused at 50 ml/min with a Krebs-albumin (3%) solution. A bolus containing [14C]dextran, [3H]BPAP, and 351A was injected and (E)351A measured by multiple indicator dilution technique. BPAP metabolism (M) was reflected by the appearance of its hydrolysis product [3H]benz-phe in lung effluent. Control (E)351A was 66 +/- 5% (mean +/- SD, n = 6) and (M)BPAP was 69 +/- 9% (n = 6). Unlabeled lisinopril (30 nmol) in the bolus significantly reduced E(351A) and M(BPAP) to 16 +/- 16% and 3 +/- 3%, respectively. Ten minutes later E(351A) and M(BPAP) had returned to control values. Reduction of E(351A) was partially reversible and M(BPAP) completely reversible after 1 min. After recirculation with 0.25 mM lisinopril for 30 min, however, significant depression of E(351A) was evident for 60 min after exposure to lisinopril was discontinued. Thus, rapid as well as slowly reversible components of inhibition of ACE inhibitor binding can be demonstrated in the perfused rabbit lung.

Albumins↗
PubMed1992

Differential uptake of endothelin-1 by the coronary and pulmonary circulations.

Substantial removal of the vasoconstrictor peptide endothelin-1 (ET-1) by the pulmonary circulation has been reported to occur in perfused guinea pig and rat lungs. We examined the uptake of ET-1 by coronary and pulmonary circulations of the rabbit by measuring single-pass extraction of ET-1 in the isolated heart and lung. In separate experiments, each organ was perfused at 30 ml/min with Krebs-albumin (3%) solution. A bolus of 125I-ET-1 and [14C]dextran in 0.3 ml Krebs-albumin solution was injected, and extraction of endothelin (EET), relative to that of an intravascular reference indicator, [14C]dextran, was determined by multiple indicator-dilution technique. EET was 5 +/- 2% (SE) in the heart and 49 +/- 4% in the lung. Increasing flow rate in the lung preparation to approximate the mean transit time in the heart preparation did not significantly alter EET. Despite insignificant uptake of ET-1, the coronary circulation extracted an angiotensin-converting enzyme inhibitor (351A) and metabolized a synthetic angiotensin-converting enzyme substrate (benzoyl-phenyl-alanyl-proline), both properties of the normal pulmonary circulation. We therefore conclude that there is no significant ET-1 uptake in the coronary vascular bed.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1992

Pulmonary vasodilation by inhaled nitric oxide after endothelial injury.

Inhaled nitric oxide gas (NO) has recently been shown to reverse experimentally induced pulmonary vasoconstriction. To examine the effect of free radical injury and methylene blue exposure on inhaled NO-induced pulmonary vasodilation we studied ventilated rabbit lungs perfused with Krebs solution containing 3% dextran and indomethacin. When NO gas (120 ppm) was added to the inhaled mixture for 3 min, the elevated pulmonary arterial perfusion pressure (Ppa) induced by the thromboxane analogue U-46619 was significantly reduced [8 +/- 2 (SE) mmHg]. Acetylcholine similarly reduced Ppa (9 +/- 1 mmHg). After free radical injury and methylene blue exposure, inhaled NO again produced significant vasodilation (5 +/- 1 and 9 +/- 2 mmHg, respectively), but acetylcholine resulted in an increase in Ppa (-9 +/- 3 and -4 +/- 1 mmHg, respectively). These data demonstrate that pulmonary vasodilation produced by inhaled NO is unaffected by free radical injury or methylene blue in the intact lung despite concomitant reversal of acetylcholine-induced vasodilation.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1992

Lisinopril and ramiprilat protection of the vascular endothelium against free radical-induced functional injury.

We reported earlier that the vasodilator response to acetylcholine (ACh) in lungs exposed to indomethacin and preconstricted with an analog of thromboxane (U46619) is converted to vasoconstriction by brief electrolysis of inflowing perfusion medium and suggested that this effect reflected endothelial injury. The purpose of our present study was 2-fold. First, because captopril, a sulfhydryl-containing inhibitor of angiotensin-converting enzyme inhibitor, prevented this effect (we assumed by scavenging electrolysis generated free radicals of oxygen), we determined whether two angiotensin-converting enzyme inhibitors lacking this moiety, namely lisinopril and ramiprilat, provided similar protection. Second, we studied whether electrolysis, like other forms of experimental lung injury, impaired uptake of serotonin (5-HT) by the endothelium. Our study confirmed that within 5 min of electrolytic injury, the ACh response is converted to vasoconstriction. This effect was completely prevented by lisinopril (18 microM) or ramiprilat (30 microM), neither of which affected ACh vasodilatation in control lungs. Lower concentrations of either drug exerted lesser degrees of protection. Five or 20 min after electrolysis, single-pass uptake of [14C]5-HT was significantly (P less than .01; N = 11) lower than control (82.4 +/- 3.4% vs. 71 +/- 3.2 and 46.5 +/- 6%, respectively). In contrast, 5-HT uptake was unaltered by electrolysis in the presence of 18 microM lisinopril. We conclude that loss of ACh vasodilation is an early reflection of lung endothelial injury that is accompanied by reduced [14C]5-HT uptake. Also, the protective property of nonsulfhydryl-containing angiotensin-converting enzyme inhibitors may be related to unexpected antioxidant actions.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1991

Endotoxin-induced exposure of pulmonary glycoproteins in an intact animal.

A method has been developed to radioiodinate luminally disposed endothelial proteins in an in situ perfused lung system without causing obvious vascular changes. The spectrum of endothelial cell proteins labeled in control animals and those treated with endotoxin for 45 min were compared. No changes in gross tissue morphology or in the distribution of radiolabel (125I-s-SHPP) were detected in control or treated lungs. Lectin affinity purification was applied to a lung membrane fraction to isolate labeled proteins, which were in turn resolved by gel electrophoresis and autoradiography. Comparisons of gel autoradiographs from control and treated lungs identified eight glycoproteins, the labeling of which was enhanced in endotoxin-treated animals. A similar lectin affinity analysis of radiolabeled effluent blood cells from the lungs identified only two proteins, neither of which were consistently changed by endotoxin pretreatment. A glycoprotein response can, therefore, be measured at the pulmonary endothelial surface on endotoxin administration to the whole animal without causing obvious lung injury.

Animals↗
PubMed1991

Effect of free radicals on pulmonary vascular response to acetylcholine.

We describe a model of pulmonary endothelial injury caused by electrolysis-generated free radicals. Rabbit lungs were perfused in situ with Krebs solution at 37 degrees C containing 30 microM indomethacin. Electrolysis of this solution for 2 min, with a constant DC current of 20 mA, caused pulmonary vasoconstriction during the passage of current and converted subsequent acetylcholine-induced vasodilation to vasoconstriction. Electrolysis also inhibited endothelial-dependent vasodilation due to the calcium ionophore A23187 but not that due to sodium nitroprusside, suggesting that smooth muscle function was unaltered, while that of the endothelium of the lung is specifically modified by the stimulus. These effects were prevented by a mixture of superoxide dismutase and catalase or by sodium salicylate, which removes hydroxyl radicals from solution after electrolysis. Electrolysis-induced endothelial damage was less functionally obvious when electrolysis was applied during recirculation of Krebs solution, perhaps because recirculating perfusion may trigger release of either free radical scavengers or other protective substances. This technique offers a simple reproducible model to study free radical-related damage of endothelium in the intact lung.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1990

Isolation of rabbit pulmonary microvascular endothelial cells and characterization of their angiotensin converting enzyme activity.

An in vitro model using cultured rabbit pulmonary endothelial cells of microvascular origin was developed to define the luminal surface membrane characteristics of microvascular endothelium. Endothelial cells were isolated from peripheral lung segments and sorted after preferential uptake of a fluorescent derivative, diiodoindocarbo cyanine acetylated-LDL. Cells were further characterized by demonstrating angiotensin converting enzyme (ACE) on their surface by means of indirect immunofluorescence. ACE activity and its pharmacologic modification were then studied as functional assays of cell activity. Hydrolysis of Benz-phe-ala-pro (BPAP), a synthetic substrate for ACE was saturable over a concentration range of 1 to 100 microns. Thus, BPAP hydrolysis in cultured microvascular endothelial cells behaves overall in a manner similar to that seen in large resistance vessels except that a portion of the hydrolysis is not inhibited by captopril, an ACE-specific inhibitor, indicating the presence of another protease capable of BPAP hydrolysis. Accordingly, this system can be used to compare ACE and other protease kinetics in microvessel cells with those of large vessel endothelium or perfused lungs.

Amino Acid Sequence↗
PubMed1990

Molecular mapping of pulmonary endothelial membrane glycoproteins of the intact rabbit lung.

To study the biochemical characteristics of endothelium in vivo, we radioiodinated endothelial membrane proteins of the perfused rabbit lung using a water soluble analog of the Bolton-Hunter reagent, 125I-sulfosuccinimidyl (hydroxyphenyl) propionate (125I-s-SHPP). This technique led to a 10-fold increase in specific activity of radioiodinated lung membrane protein compared with our previously reported method using lactoperoxidase and glucose oxidase-catalyzed radioiodination. Tissue autoradiography confirmed that radioiodination was largely confined to the endothelium. Perfusion pressure, wet-to-dry weight ratios, and the morphological appearance of the lungs were within normal limits, indicating that the procedure does not cause apparent lung injury. Lectin binding to a crude membrane fraction of 125I-s-SHPP labeled lung led to isolation of several putative endothelial membrane proteins. Immunoprecipitation studies with appropriate antibodies enabled the identification of radioiodinated angiotensin-converting enzyme and beta 2-microglobulin associated major histocompatibility complex class I molecules in the membrane fraction. This technique will be useful for studying biochemical responses of the endothelium in vivo to a variety of pharmacological and physiology stimuli.

Animals↗
PubMed1990

Disposition of radioiodinated benzylguanidines in perfused rabbit lung: pharmacokinetics and effect of an organo-gold complexed antineoplastic agent.

SK&F 104524 (bis-[1,2-bis(diphenylphosphino)-ethane]-gold(I)-lactate) ([Au(dppe)2]+) is a lipophilic phosphine-coordinated gold complex that has significant antineoplastic activity. However, this agent has significant hepato- and cardiotoxicity and preclinical preliminary experiments indicate potential pneumotoxic effects. Accordingly, we sought to evaluate the acute effects of [Au(dppe)2]+ on pulmonary removal of two radioiodinated benzylguanidines [metaiodobenzylguanidine (MIBG) and 3-iodo-4-amino-benzylguanidine (AIBG)]. Pulmonary removal of MIBG or AIBG was measured by application of indicator dilution techniques in rabbit lungs, perfused with Kreb's bicarbonate (3% albumin; 50 ml/min). A bolus containing either [125I]MIBG or--AIBG and [99mTc]sulfur colloid was injected into the pulmonary artery and effluent was diverted to an in-line nuclear detection system. In initial experiments we characterized some pharmacokinetic aspects of the disposition of these amines. Removal of MIBG [R(MIBG)] and R(AIBG) were 59 +/- 3% (n = 14) and 24 +/- 2% (n = 7), respectively. Addition of unlabeled norepinephrine, MIBG or AIBG (3-100 nmol) to the injection caused similar dose-dependent reductions in removal of either amine. Lowering the temperature (13 degrees C) or reducing the sodium concentration caused significant reductions in removal. After 15 min of perfusion with [Au(dppe)2]+ (50 micrograms/ml), perfusion pressure doubled and R(MIBG) and R(AIBG) were each decreased significantly. At 30 min, perfusion pressure returned to control values whereas there was still a 36 and 61% reduction in R(MIBG) and R(AIBG), respectively. These data confirm that removal of benzylguanidines involves a saturable, sodium- and temperature-dependent process similar to that responsible for the removal of norepinephrine.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Iodobenzylguanidine↗
PubMed1990

Pulmonary endothelial cell injury and altered lung metabolic function. Early detection of the adult respiratory distress syndrome and possible functional significance.

Markers of endothelial cell damage or dysfunction may be sensitive probes for the detection of the earliest phases of acute lung injury and may be a guide to the severity of injury or response to therapy as well. Depressed lung metabolic function may contribute to the intrapulmonary or systemic pathophysiology of ARDS.

Animals↗
PubMed1979

Indicator dilution measurement of 5-hydroxytryptamine clearance by human lung.

A double indicator dilution method to measure 5-hydroxytryptamine (5-HT) clearance by lungs of anesthetized patients is described. Immediately after a bolus injection of [3H]dextran and [14C]5-HT into the right atrial port of a Swan-Ganz catheter, blood from the radial artery is fractionated and the tritium and carbon-14 of each fraction is measured. The difference between the normalized curves of dextran and 5-HT vs. time reflect the extent to which 5-HT is extracted by the lung. This method gave a mean value of 61 +/- 3% (n = 10) for extraction of 5-HT, compared to 59 +/- 4% measured simultaneously by means of the pulmonary artery-left atrial gradient of 5-HT. Variations among three successive determinations in each patient made postoperatively were not statistically significant. This technique is applicable whenever Swan-Ganz and radial or brachial artery catheters are placed for routine clinical management and, therefore, may have wide application for measurement of pulmonary amine (or kinin) extraction in conscious human subjects or experimental animals. Because pulmonay clearance may be compromised by endothelial damage, 5-HT extraction measured in this manner could reflect early damage to human pulmonary endothelium--perhaps before clinical evidence of damage, such as interstitial edema and respiratory distress, is evident.

Carbon Radioisotopes↗
PubMed1978

Effects of monocrotaline pretreatment of rats on removal of 5-hydroxytryptamine and noradrenaline by perfused lung.

1 The alkaloid, monocrotaline, causes significant pulmonary damage in many species, including the rat. We, therefore, determined whether the inactivation of biogenic amines by perfused lungs of rats was modified by prior treatment of the animals with monocrotaline.2 Young rats (45 to 50 g) treated for 21 days with monocrotaline (22 mug/ml) in their drinking water developed right ventricular hypertrophy. Treated animals gained weight more slowly and consumed less food and water than control rats that drank tap water. Lungs from monocrotaline-treated animals were heavier and had a higher protein content than control lungs.3 Isolated lungs from treated animals removed and metabolized 50% less perfused 5-hydroxytryptamine than did controls.4 The diminished 5-hydroxytryptamine metabolism was probably due to impaired delivery of substrate to intrapulmonary monoamine oxidase (MAO) since MAO activity in 600 g supernatant fractions of homogenates of lungs from monocrotaline-treated rats was not different from control values.5 Pulmonary removal of perfused noradrenaline was decreased about 60% by the 21-day treatment, suggesting that the effects of monocrotaline were somewhat nonspecific.6 These effects were not caused by monocrotaline directly, since perfusion of lungs from untreated animals with this drug did not alter removal of co-perfused 5-hydroxytryptamine.7 Reduced pulmonary removal of circulating biogenic amines following pretreatment with monocrotaline may reflect damage to capillary endothelium, which could also affect other metabolic functions of lung.

Animals↗