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PubMed1995

The inhibitory effect of 3-amino-1,2,4-triazole on relaxation induced by hydroxylamine and sodium azide but not hydrogen peroxide or glyceryl trinitrate in rat aorta.

1. In this study we investigated the role of catalase in relaxation induced by hydroxylamine, sodium azide, glyceryl trinitrate and hydrogen peroxide in isolated rings of rat aorta. 2. Hydrogen peroxide (1 microM-1 mM)-induced concentration-dependent relaxation of phenylephrine (PE)-induced tone in endothelium-containing rings. In endothelium-denuded rings, however, higher concentrations (30 microM-1 mM) of hydrogen peroxide were required to produce relaxation. The endothelium-dependent component of hydrogen peroxide-induced relaxation was abolished following pretreatment with N(O)-nitro-L-arginine methyl ester (L-NAME, 30 microM). L-NAME (30 microM) had no effect, however, on hydrogen peroxide-induced relaxation in endothelium-denuded rings. 3. Pretreatment of endothelium-denuded rings with catalase (1000 u ml-1) blocked relaxation induced by hydrogen peroxide (10 microM-1 mM). The ability of catalase to inhibit hydrogen peroxide-induced relaxation was partially blocked following incubation with 3-amino-1,2, 4-triazole (AT, 50 mM) for 30 min and completely blocked at 90 min. 4. Pretreatment of endothelium-denuded rings with methylene blue (MeB, 30 microM) inhibited relaxation induced by hydrogen peroxide (10 microM-1 mM), sodium azide (1-300 nM), hydroxylamine (1-300 nM) and glyceryl trinitrate (1-100 nM) suggesting that each acted by stimulation of soluble guanylate cyclase. 5. Pretreatment of endothelium-denuded rings with AT (1-50 mM, 90 min) to inhibit endogenous catalase blocked relaxation induced by sodium azide (1-300 nM) and hydroxylamine (1-300 nM) but had no effect on relaxation induced by hydrogen peroxide (10 microM-1 mM) or glyceryl trinitrate (1-100 nM). 6. In a cell-free system, incubation of sodium azide (10 microM-3 mM) and hydroxylamine (10 microM-30 mM) but not glyceryl trinitrate (10 microM-1 mM) with catalase (1000 u ml-1) in the presence of hydrogen peroxide (1 mM) led to production of nitrite, a major breakdown product of nitric oxide. AT (1-100 mM) inhibited, in a concentration-dependent manner, the formation of nitrite from azide in the presence of hydrogen peroxide. 7. These data suggest that metabolism by catalase plays an important role in the relaxation induced by hydroxylamine and sodium azide in isolated rings of rat aorta. Relaxation appears to be due to formation of nitric oxide and activation of soluble guanylate cyclase. In contrast, metabolism by catalase does not appear to be involved in the relaxant actions of hydrogen peroxide or glyceryl trinitrate.

Amitrole↗

PubMed1983

Increased coronary sinus lactate concentration during pacing induced angina pectoris after clinical improvement by glyceryl trinitrate.

Ten patients with stable angina pectoris and obstructed coronary arteries (greater than 75% reduction in diameter) were studied before and during two periods of pacing, the second of which was preceded by sublingual administration of glyceryl trinitrate (mean dose 0.78 mg). Coronary sinus blood flow measurements and aortocoronary sinus blood sampling for metabolite determinations were carried out. Although the rate of pacing was increased by 10 beats/minute after glyceryl trinitrate administration, the onset of angina was delayed in eight patients during pacing. Drug administration decreased coronary sinus blood flow by 42% and myocardial oxygen uptake by 41% during pacing and induced a shift in mean lactate extraction towards a net release (from 3.1% to -12.6%). It increased the number of patients producing lactate from three to five. Glyceryl trinitrate administration decreased myocardial glucose uptake throughout the study, decreased lactate extraction during recovery, and increased the aortocoronary sinus citrate gradient at rest and during recovery, while the exchange of free fatty acids remained unchanged. A decrease in aortocoronary sinus lactate difference during pacing after glyceryl trinitrate administration correlated positively with the fall in coronary sinus blood flow. The metabolic data do not indicate an augmented myocardial lactate production after glyceryl trinitrate administration. A decrease in coronary sinus blood flow seems, therefore, to be of primary importance in explaining the elevated coronary sinus lactate concentration. Our finding that coronary sinus lactate concentration increased during pacing after glyceryl trinitrate administration despite clinical improvement questions the validity of its use as a quantitative index of ischaemia.

Adult↗

PubMed2006

Botulinum toxin vs. topical glyceryl trinitrate ointment for pain control in patients undergoing hemorrhoidectomy: a randomized trial.

PURPOSE: The maximum resting pressure in the anal canal is greatly raised after hemorrhoidectomy. This increase is likely to be the cause of postoperative pain, which is still the most troublesome early problem after hemorrhoidectomy. This study was designed to compare, after hemorrhoidectomy, the effects of intrasphincter injection of botulinum toxin vs. application of glyceryl trinitrate ointment in improving wound healing and reducing postoperative pain at rest or during defecation. METHODS: Thirty patients with hemorrhoids of third and fourth degree were included in the study and randomized in two groups. Anorectal manometry was performed preoperatively and 5 and 40 days after hemorrhoidectomy. One group received one injection containing 20 IU of botulinum toxin, whereas the other an application of 300 mg of 0.2 percent glyceryl trinitrate ointment three times daily for 30 days. RESULTS: Five days after hemorrhoidectomy, maximum resting pressure was significantly reduced compared with baseline values in both groups (85 +/- 15 vs. 68 +/- 11 mmHg for the group treated with botulinum toxin, 87 +/- 11 vs. 78 +/- 11 mmHg for the group treated with glyceryl trinitrate ointment). Overall analysis of postoperative pain at rest showed a significant reduction in the botulinum toxin group vs. glyceryl trinitrate group, whereas pain during defecation and time of healing were similar. Adverse effects, such as headaches, were observed only in the glyceryl trinitrate group. Forty days after hemorrhoidectomy in the glyceryl trinitrate group, maximum resting pressure values were similar to preoperative ones, whereas the values were still reduced in the botulinum toxin group. CONCLUSIONS: A single intrasphincter injection of botulinum toxin was more effective and safer than repeated applications of glyceryl trinitrate in reducing early postoperative pain at rest but not during defecation.

Adult↗

PubMed1989

Automatic control of arterial pressure after cardiac surgery. Evaluation of a microcomputer-based control system using glyceryl trinitrate and sodium nitroprusside.

Arterial hypertension after cardiac surgery is common and is associated with increased morbidity. Glyceryl trinitrate may be a more suitable agent for control of hypertension than sodium nitroprusside. We have developed a closed-loop system for the Atari 1040ST microcomputer to control arterial pressure by the simultaneous infusion of two vasodilators under computer control. Use of this system with glyceryl trinitrate and sodium nitroprusside in 24 patients who required vasodilators after cardiopulmonary bypass, revealed that hypertension was controlled by glyceryl trinitrate alone in 14 of the patients and 10 required supplementary sodium nitroprusside. The results suggest that glyceryl trinitrate is a suitable agent for control of hypertension after cardiac surgery in the majority of patients. They also show that a sizeable minority required additional sodium nitroprusside, and that an automated 'dual pump' system is a satisfactory method of administering two vasodilators in this way.

Cardiac Surgical Procedures↗

PubMed1990

Local application of EMLA and glyceryl trinitrate ointment before venepuncture.

One hundred unpremedicated fit day surgery patients aged between 27 and 68 years were allocated randomly into one of four groups and EMLA, glyceryl trinitrate, EMLA and glyceryl trinitrate or a placebo ointment was applied to the dorsum of a hand. The pain and ease of venepuncture were determined at induction of anaesthesia 60 minutes later. Pain scores were also reassessed 1-2 hours after operation. Lower pain scores and easier venepuncture occurred when EMLA and glyceryl trinitrate ointment was applied to the dorsum of the hand.

Administration, Cutaneous↗

PubMed1997

The effects of glyceryl trinitrate and nicotinic acid ointments during cold exposure.

The aim of the present experimental study was to examine the effects of local application of glyceryl trinitrate and nicotinic acid on the cold-provoked haemodynamic responses, pain and hand dexterity. Ten young healthy volunteers participated in this randomized, cross-over study with three phases at least two days apart. Five cm of 2% glyceryl trinitrate ointment, 10% nicotinic acid ointment or placebo ointment was applied on the back of each subject's both hands 15 min. before the 7 min. cold exposure. Blood pressure and heart rate were measured prior to, during and after the cold exposure. In addition, the effect of cold on hand dexterity was evaluated by the Purdue pegboard test and the subjects assessed the pain in their hands during the cold exposure. Pretreatment with glyceryl trinitrate ointment counteracted the cold-induced haemodynamic response, as evidenced by a significantly (P < 0.05) smaller mean increase in the systolic blood pressure from the baseline compared with placebo. In contrast, the cold-induced increase in the systolic blood pressure observed after pretreatment with nicotinic acid ointment did not differ from placebo. Both glyceryl trinitrate and nicotinic acid alleviated the cold-induced pain, but neither of them prevented the deterioration of hand dexterity. In conclusion, the haemodynamic response provoked by a brief cold exposure could to some extent be counteracted by pretreatment with glyceryl trinitrate ointment, but not with nicotinic acid ointment, compared with placebo.

Administration, Topical↗

PubMed1995

Effects of nicorandil and glyceryl trinitrate on infarct size, adenosine release, and neutrophil infiltration in the dog.

OBJECTIVE: The major aim of this study was to determine if nicorandil, a potassium channel opener nitrate, produces a reduction in myocardial infarct size at a non-hypotensive dose in dogs and to determine if this effect is the result of an increase in adenosine release or reduction in neutrophil infiltration into the ischaemic area. Glyceryl trinitrate was used for purposes of comparison. METHODS: Barbitone anaesthetised dogs were subjected to 60 min of left anterior descending coronary artery occlusion followed by 3 h of reperfusion. Nicorandil (100 microgram.kg-1 bolus followed by a 10 microgram.kg-1.min-1 infusion; NC/pre group), glyceryl trinitrate (10 microgram.kg-1 bolus followed by a 1 microgram.kg-1.min-1 infusion; GTN/pre group), or an equivalent volume of saline (control group) were given intravenously 15 min before occlusion and continued to the time of reperfusion. In two other groups, nicorandil (NC/post group) or glyceryl trinitrate (GTN/post group) were given 10 min before reperfusion and continued until the end of the experiment. To measure the release of adenosine from the ischaemic region, coronary venous blood samples were collected before occlusion, during occlusion, and at various times following reperfusion. Myocardial infarct size was determined by triphenyltetrazolium chloride and transmural myocardial blood flow by radioactive microspheres. Transmural myeloperoxidase activity, an index of neutrophil infiltration, was measured in biopsies obtained from the area at risk. RESULTS: Pretreatment with nicorandil and glyceryl trinitrate caused a marked reduction in myocardial infarct size expressed as percent of the area at risk [NC/pre group, 7.8(SEM 1.6)%; GTN/pre group, 11.9(2.3)%; control group, 31.0(5.6)%]. When nicorandil and glyceryl trinitrate were given before reperfusion, both drugs still produced a significant reduction in infarct size [NC/post group, 13.8(2.0)%; GTN/post group, 18.9(4.3)%]. Coronary venous adenosine concentrations during reperfusion were significantly lower in both nicorandil and glyceryl trinitrate pretreated groups, but not in the post-treated groups. Transmural myeloperoxidase activity was significantly lower in both nicorandil treated groups. CONCLUSIONS: Pretreatment with a non-hypotensive dose of nicorandil or glyceryl trinitrate markedly reduces myocardial infarct size and adenosine release from the ischaemic-reperfused area. These agents were also effective, but to a lesser degree, when given just before reperfusion. The cardioprotective actions of nicorandil appear to be related not only to its potassium channel opening activity but also in part to its nitrate activity.

Adenosine↗

PubMed1978

Coronary and myocardial metabolic effects of combined glyceryl trinitrate and propranolol administration. Observations in patients with and without coronary disease.

Coronary haemodynamic and metabolic effects of propranolol and glyceryl trinitrate were studied in 12 patients with coronary artery disease and 5 without coronary heart disease, at rest and during tachycardia stress. Propranolol-associated reductions in indices of myocardial oxygen demand, left ventricle work, tension time, and left ventricle oxygen utilisation (LVVO2) were reversed when heart rate was controlled by atrial pacing. Adding glyceryl trinitrate at rest also restored heart rate but decreased the left ventricular work index and tension time index as coronary resistance declined paradoxically. Tachycardia-related increases in tension time index and LVVO2 were unchanged after propranolol, and ischaemia (angina, ST depression, and reduced lactate extraction) was not altered in most of the patients. During tachycardia, the addition of glyceryl trinitrate decreased the tension time index and LVVO2; angina recurred in only 4 patients, and ST depression and lactate extraction improved. Similar haemodynamic changes occurred in the patients with normal coronary arteries. In contrast with propranolol administered alone, propranolol plus glyceryl trinitrate enhances tachycardia tolerance and prevents tachycardia-induced manifestations of ischaemia. This action is attributed to glyceryl trinitrate-associated improvement in the adequacy of myocardial perfusion.

Adult↗

PubMed1977

Blood levels of the metabolites of glyceryl trinitrate and pentaerythritol tetranitrate after administration of a two-step preparation.

Blood levels and urinary excretion rates of glyceryl trinitrate- pentaerythritol tetranitrate, and their less nitrate containing metabolites have been determined in ten human volunteers after a single dose of a two- step preparation containing glyceryl trinitrate and pentaerythritol tetranitrate. Blood levels accounted for peak levels of about 40% of the glyceryl trinitrate and 0.4% of the pentaerythritol tetranitrate metabolites, respectively. Within the first 24 h post administration 22% of the glyceryl trinitrate and 19% of the pentaerythritol tetranitrate were excreted as nitrate metabolites, chiefly in form of conjugates. The determinations were obtained by gas chromatography on extremely inactive columns and electron capture detection by means of derivatives.

Adult↗

PubMed2006

Intravaginal glyceryl trinitrate and dinoprostone for cervical ripening and induction of labor.

OBJECTIVE: This study was undertaken to evaluate the efficacy and safety of intravaginal administration of glyceryl trinitrate plus dinoprostone versus dinoprostone, for cervical ripening and induction of labor. STUDY DESIGN: A prospective, double-blind, placebo-controlled, randomized clinical trial was conducted among 196 singleton low-risk nullipara women with term pregnancies and unfavorable cervices who were randomly assigned to receive intravaginal glyceryl trinitrate plus dinoprostone or placebo plus dinoprostone. The main outcome variables were time from application to active phase of labor and to delivery. Secondary outcomes were change in Bishop score, fetal and maternal morbidity, and incidence of cesarean deliveries. RESULTS: The interval from application of the initial dose to the beginning of active phase of labor was 868 +/- 582 and 1136 +/- 692 minutes (P = .004) and from initial dose to delivery was 1339 +/- 826 and 1620 +/- 975 minutes (P = .03) for the glyceryl trinitrate and placebo groups, respectively. There were no significant differences in Bishop score change, cesarean section rate, and in the incidence of hypersystole and hyperstimulation. The incidence of tachysystole was significantly lower in the glyceryl trinitrate group (4% vs 15%, P < or = .02). No maternal and neonatal adverse effects were noted. CONCLUSION: The association of glyceryl trinitrate with dinoprostone is more effective than dinoprostone alone for labor induction in low-risk patients at term with unfavorable cervices.

Administration, Intravaginal↗

PubMedDate not supplied

An acute double-blind placebo-controlled study of transdermal glyceryl trinitrate with 12 months' follow-up in patients with stable angina pectoris.

In an acute double-blind placebo-controlled randomized crossover study, 1 day of treatment with a glyceryl trinitrate transdermal patch releasing 10 mg glyceryl trinitrate daily was compared with placebo in 40 men with stable angina pectoris. Subsequently, the patients participated in an uncontrolled efficacy and tolerability study during which the transdermal patch was applied to the front of the chest for 22-23 hours daily for 12 months. In the acute study, one patch of glyceryl trinitrate or matching placebo was applied at 8.00 a.m. for 24 h; 48 h later the other treatment was applied. Bicycle ergometry was performed 24 and 16 h before the beginning of the treatment, and 8 and 24 h after each dose. Ergometry was repeated after 1, 3, 6 and 12 months' treatment with one patch daily of glyceryl trinitrate during the long-term open follow-up study. In the acute study, a significant reduction of ST-segment depression was observed with treatment compared with placebo. This reduction persisted throughout the 12 months of the open study. During this period also, the mean number of anginal attacks was reduced from 5.3 to 3.6 during week 1 of treatment, and this reduction was maintained throughout the 12 months of the study. No patient needed to be withdrawn because of systemic side-effects or local intolerance to the patch.

Administration, Cutaneous↗

PubMed1987

Effects of glyceryl trinitrate on endothelium-dependent and -independent relaxation and cyclic GMP levels in rat aorta and human coronary artery.

The effects of glyceryl trinitrate-induced desensitization on relaxations and/or elevated cyclic GMP levels due to the nitrogen oxide-containing vasodilators (glyceryl trinitrate and sodium nitroprusside), the endothelium-dependent vasodilators (acetylcholine and the Ca2+ ionophore A23187), and the atrial peptides (atriopeptin II) were investigated in the rat thoracic aorta and human coronary artery. Prior exposure of rat thoracic aorta to glyceryl trinitrate decreased relaxations to glyceryl trinitrate, sodium nitroprusside, and acetylcholine, whereas relaxations to atriopeptin II and 8-bromo cyclic GMP remained unaltered. In human coronary artery, glyceryl trinitrate pretreatment inhibited relaxations to glyceryl trinitrate, sodium nitroprusside, and the Ca2+ ionophore A23187. Relaxation to glyceryl trinitrate was inhibited more than that to sodium nitroprusside in both tissues. Acetylcholine-induced relaxation in rat thoracic aorta was slightly inhibited, whereas relaxation to the Ca2+ ionophore A23187 in human coronary artery was markedly depressed. Pretreatment with glyceryl trinitrate decreased the elevated cyclic GMP levels due to glyceryl trinitrate and acetylcholine in rat thoracic aorta and to glyceryl trinitrate and the Ca2+ ionophore A23187 in human coronary artery. Removal of the endothelium abolished the increased cyclic GMP levels and relaxation due to the Ca2+ ionophore A23187 and decreased basal cyclic GMP levels in the human coronary artery. In contrast, atriopeptin II-induced increased cyclic GMP levels were unaltered by glyceryl trinitrate pretreatment in rat thoracic aorta. The present results suggest that: glyceryl trinitrate-induced desensitization inhibits relaxation to the nitrogen oxide-containing vasodilators and endothelium-dependent vasodilators in both the rat thoracic aorta and human coronary artery: the inhibition of relaxation is associated with decreased formation of cyclic GMP;(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗

PubMed1999

24-hour ambulatory blood pressure monitoring: a comparison between transdermal glyceryl-trinitrate and oral nifedipine.

The objective of the present study is to compare the effectiveness of transdermal glyceryl-trinitrate versus oral nifedipine in lowering blood pressure in patients affected by pregnancy-induced hypertension (PIH). Thirty-six consecutive pregnant women have been evaluated at different gestational ages after the diagnosis of PIH or preeclampsia (PE). After a 24-h ambulatory blood pressure monitoring, patients were allocated to three groups: those receiving oral nifedipine and those receiving transdermal glyceryl-trinitrate in a continuous (24 h/day) or intermittent (16 h/day) administration. A second blood pressure monitoring was performed after 2 weeks of treatment. Systolic and diastolic blood pressure were compared by using the Cosinor method looking at mesor, amplitude, and acrophase. Baseline systolic and diastolic blood pressure was similar among the three groups. Neither the transdermal glyceryl-trinitrate administered for 24 or 16 h nor oral nifedipine affected systolic and diastolic blood pressure. Analysis of variance showed that the posttreatment values were similar among the groups. Further studies are needed to verify the possible use of transdermal glyceryl-trinitrate as an antihypertensive drug during pregnancy.

Administration, Cutaneous↗

PubMed1985

Absolute bioavailability of glyceryl trinitrate from a transdermal system, assessed by digital plethysmography.

The absolute bioavailability of glyceryl trinitrate from a transdermal therapeutic system (Nitroderm TTS, 20 cm2) was assessed with a new method in 6 healthy volunteers. Instead of measuring plasma concentrations the pharmacological effects of glyceryl trinitrate were followed by digital plethysmography. Each experiment consisted of the establishment of an intravenous dose response curve which was followed by a 1-hour application of the transdermal system and a second intravenous dose response curve. The investigations were repeated after pretreatment of each subject with 0.4 mg pindolol i.v. The results show a satisfactory overall consistency of the data and indicate a release rate of 4.4 +/- SD 1.7 micrograms/min of bioavailable glyceryl trinitrate during the first hour of application of this transdermal system. This corresponds to 75 +/- 29% of the release rate obtained by analysis of residual amounts in the TTS.

Administration, Topical↗

PubMed1982

Determination of glyceryl trinitrate in human plasma by gas chromatography--negative ion chemical ionization--selected ion monitoring.

A specific, sensitive and accurate quantitation method for glyceryl trinitrate was developed using gas chromatography--negative ion chemical ionization--selected ion monitoring with dichloromethane as a reagent gas. [15N3] and [2H5, 15N3] variants were synthesized from non-labelled or [2H8]glycerol and [15N]nitric acid. The former variant was used for preventing adsorption of glyceryl trinitrate onto active sites on column materials and the latter was used as an internal standard for quantitation of glyceryl trinitrate in biological fluids by selected ion monitoring. The quantitation limit of this method is 0.1 ng/ml of human plasma. When glyceryl trinitrate was administered intravenously in the dose of 4 micrograms/kg to patients receiving hypotensive anesthesia for surgical operation, the plasma levels exhibited a biexponential decay. The mean and standard deviation of half-lives of the alpha and beta phases were found to be about 0.41 +/- 0.13 and 5.34 +/- 1.60 min, respectively.

Adult↗

PubMed1990

Inhibitors of cytochrome P-450 reduce cyclic GMP stimulation by glyceryl trinitrate in LLC-PK1 kidney epithelial cells.

The inhibitor of cytochrome P-450 cimetidine was used to assess the role of cytochrome P-450-dependent enzymes for cyclic GMP stimulation by glyceryl trinitrate in a kidney epithelial cell line (LLC-PK1). Pretreatment of the cells with 0.1 mmol/l cimetidine markedly decreased cyclic GMP stimulation by glyceryl trinitrate (0.03-1 mumol/l). In the presence of 0.1 mmol/l cimetidine, the 14-fold cyclic GMP stimulation observed at 1 mumol/l glyceryl trinitrate was reduced by 66%. Glyceryl trinitrate-induced cyclic GMP stimulation remained unaltered by ranitidine (0.1 mmol/l), which has a much lower affinity for the cytochrome P-450 enzyme system. Another inhibitor of cytochrome P-450, miconazole (0.1 mmol/l), also attenuated glyceryl trinitrate-induced cyclic GMP stimulation. In contrast, cimetidine and miconazole did not affect cyclic GMP stimulation by sodium nitroprusside that spontaneously releases nitric oxide. These results suggest that in intact cells, glyceryl trinitrate-induced cyclic GMP stimulation is dependent on cytochrome P-450 enzymes which may be relevant for nitric oxide formation from organic nitrates.

Animals↗

PubMed1983

The effects of glyceryl trinitrate, isosorbide dinitrate and sodium nitroprusside on haemodynamics, coronary blood flow and myocardial oxygen consumption - an experimental study.

The influences of glyceryl trinitrate, isosorbide dinitrate and sodium nitroprusside intravenously on haemodynamics, coronary circulation and myocardial oxygen consumption were investigated in closed chest dogs (n = 8). In an attempt to simulate heart failure the dogs received blood transfusion (15 ml/kg) in the presence of halothane-induced myocardial depression. All three nitrates reduced the loads for the left ventricle. With isosorbide dinitrate and sodium nitroprusside the preload and pulmonary pressure decreased to a greater extent than with glyceryl trinitrate. The haemodynamic results suggest that sodium nitroprusside is the favourable nitrate in left ventricular failure because it produces a balanced reduction in the ratio of pre- and afterload. Four micrograms/kg X min sodium nitroprusside induced marked coronary dilatation; glyceryl trinitrate had only a slight coronary vasodilating effect. With isosorbide dinitrate the myocardial blood flow remained well adapted to oxygen demand, the coronary vascular resistance did not change. Sodium nitroprusside produced a significant change of the transmural myocardial blood distribution-expressed as the epi/endocardial blood flow ratio. The ratio was increased by sodium nitroprusside, much more than by glyceryl trinitrate or isosorbide dinitrate.

Animals↗

PubMed1986

Influence of glyceryl trinitrate and nifedipine on coronary sinus blood flow and global myocardial metabolism during coronary artery operation.

The effects of intravenous infusions of glyceryl trinitrate and nifedipine on systemic haemodynamic function, coronary haemodynamic function, and global myocardial metabolism were compared in two groups of eleven patients with unimpaired left ventricular function undergoing elective coronary artery operation who were anaesthetised with high dose fentanyl. Severe post-sternotomy hypertension developed in three patients in the glyceryl trinitrate group who were resistant to the hypotensive effect of this agent. All patients given nifedipine remained haemodynamically stable. Coronary sinus blood flow and myocardial oxygen consumption increased and coronary vascular resistance decreased after sternotomy in the nifedipine group but not in the glyceryl trinitrate group. There is no satisfactory explanation for the apparently paradoxical increase in myocardial oxygen consumption in the patients given nifedipine. This phenomenon did not appear to be associated with any detrimental effect of left ventricular function. Thus nifedipine was better than glyceryl trinitrate for the control of post-sternotomy hypertension in patients with good left ventricular function. Intravenous nifedipine is not recommended, however, for the intraoperative control of blood pressure in patients with unstable angina or impaired left ventricular function.

Blood Flow Velocity↗