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At least 19 recordsLinked to original sources
PubMed1986

The kinetic differences between sodium nitrite, amyl nitrite and nitroglycerin oxidation of hemoglobin.

The effect of sodium nitrite, amyl nitrite and nitroglycerin (glyceryl trinitrate) on the hemoglobin of adult erythrocytes was examined in vitro. Both amyl nitrite and nitroglycerin reacted immediately with oxyhemoglobin to effect oxidation into methemoglobin while sodium nitrite required an inductionary period (lag phase) prior to the reaction. Kinetic studies of the biomolecular rate law for each of the preceding reaction's reactionary periods (log phases) allowed rate constant calculations to be made. The values are 1.14 x 10(4) M-1 min-1, 7.45 x 10(4) M-1 min-1, and 3.50 x 10(1) M-1 min-1 for sodium nitrite, amyl nitrite and nitroglycerin, respectively. A comparison of the amyl nitrite and nitroglycerin rate constants reveals that amyl nitrite is approximately 2000-fold more toxic to oxyhemoglobin than nitroglycerin. These oxidant's effect on in vitro hemoglobin solutions are comparable since both reactions approximate to rectangular hyperbolae. Sodium nitrite reacts about 300-fold faster with oxyhemoglobin than does nitroglycerin. However, the sodium nitrite reaction proceeds in a sigmoidal fashion which makes a strict comparison between these compounds relative toxicities less clear cut.

Erythrocytes↗
PubMed1981

Methylene blue inhibits coronary arterial relaxation and guanylate cyclase activation by nitroglycerin, sodium nitrite, and amyl nitrite.

Relaxation by nitroglycerin, sodium nitrite, and amyl nitrite of bovine coronary arterial smooth muscle was inhibited by the oxidant methylene blue. Methylene blue also inhibited activation of bovine coronary arterial soluble guanylate cyclase by nitroglycerin, which required addition of cysteine. At concentrations less than 10 mM, sodium nitrite required the addition of one of several thiols or ascorbate to activate guanylate cyclase from bovine coronary artery. Guanylate cyclase activation by large amounts (50 microL) of saturated amyl nitrite gas did not require, but was enhanced by, the addition of thiols or ascorbate. However, similar to sodium nitrite, guanylate cyclase activation by smaller amounts (5 microL) of saturated amyl nitrite gas did require the addition of one of various thiols or ascorbate. Methylene blue markedly inhibited guanylate cyclase activation by sodium nitrite in the presence of cysteine or ascorbate and similarly inhibited enzyme activation by amyl nitrite either in the absence or presence of cysteine or ascorbate. These data support the hypothesis that nitrates and nitrites relax vascular smooth muscle by stimulating cyclic GMP formation. The results further suggest that, similar to relaxation and guanylate cyclase activation by nitroso-containing compounds, relaxation and enzyme activation by nitrates and and nitrites may involve the formation of nitric oxide or complexes of nitric oxide as active intermediates.

Amyl Nitrite↗
PubMed2000

Amyl nitrite induced acute haemolytic anaemia in HIV-antibody positive man.

Volatile nitrites (amyl and butyl) are popular recreational drugs, especially in the homosexual population. Haemolytic anaemia is a rare complication of nitrite inhalation and occurs when the reducing capacity of the red cell enzymes is overcome by the oxidizing effect of the nitrite. We describe here a patient with HIV infection who developed a profound haemolytic anaemia after repeated inhalation of large quantities of amyl nitrite.

Acute Disease↗
PubMed1995

Provocation of latent left ventricular outflow tract gradients with amyl nitrite and exercise in hypertrophic cardiomyopathy.

Amyl nitrite may be used to provoke latent gradients in patients with hypertrophic cardiomyopathy (HC) without significant resting outflow tract gradients, but afterload reduction may not be comparable to a more physiologic stressor such as symptom-limited exercise testing. This study compared the ability of amyl nitrite and exercise testing to provoke outflow tract gradients in 57 patients (40 men and 17 women, mean age +/- SD 49 +/- 16 years) with HC (septal thickness 19 +/- 5 mm, average resting gradient 13 +/- 10 mm Hg) who underwent echocardiography at rest, after amyl nitrite inhalation, and after maximal exercise. No significant gradient (< 50 mm Hg) was induced after either provocation in 26 patients (46%); in 15 patients (26%), inducibility was achieved after both stressors, in 6 (11%) after exercise only, and in 10 (18%) after amyl only. Patients with amyl-induced gradients differed from those in whom gradients were noninducible on the basis of smaller outflow tract dimensions (p < 0.001), larger resting gradients (p < 0.001), and a greater prevalence of "septal bulge" morphology (p = 0.02). Those with exercise-induced gradients were able to attain a greater workload (p = 0.07), have larger resting gradients (p = 0.02), and also tended to have a septal bulge morphology (p < or = 0.01). Although outflow tract obstruction increased to similar levels after amyl nitrite (49 +/- 39 mm Hg) and symptom-limited exercise (47 +/- 39 mm Hg), gradients induced by exercise and amyl correlated poorly (r = 0.54).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Inhalation↗
PubMed1992

Amyl nitrite: use as a smooth muscle relaxant in difficult preterm cesarean section.

Amyl nitrite is a smooth muscle relaxant that has been used clinically to facilitate uterine relaxation in difficult deliveries. In this retrospective study, we evaluate the safety of amyl nitrite use during preterm cesarean deliveries, and we assess possible advantageous effects on surgical incision choice. Women who received amyl nitrite cesarean section were compared to a control group matched for gestational age, fetal presentation, and mode of delivery who did not receive amyl nitrite. There were no statistical differences between the groups in the independent variables (maternal age, parity, medical or obstetric history, type of anesthesia, anesthesia or obstetric attending physician, antepartum hematocrit, or neonatal weight). Outcome (dependent) variables (estimated blood loss, Apgar scores, postpartum hematocrit, cord gases, or postpartum complications) were assessed, and there were no significant differences between the groups. Low transverse cesarean section was performed more frequently in the amyl nitrite group (58 of 64) than in the comparison group (48 of 64) (p less than 0.03). Considering the 128 women with and without amyl nitrite together, the decrease in hematocrit observed postpartum was greater after classic section (7%) than after low transverse section (4%) (p less than 0.002). We conclude that the use of amyl nitrite during preterm cesarean section poses no threat to mother or fetus and may facilitate delivery by allowing the performance of a low transverse rather than a classic cesarean section without maternal or neonatal complications.

Amyl Nitrite↗
PubMed1986

Radiologic amyl nitrite test for distinguishing pseudoachalasia from idiopathic achalasia.

In a simple radiologic test, amyl nitrite inhalation seems to distinguish patients with pseudoachalasia from those with idiopathic achalasia. In three pseudoachalasia patients with tumor infiltration of the distal esophagus, the narrow lower esophageal sphincter segment was unaffected by the smooth-muscle relaxant effect of amyl nitrite. In contrast, amyl nitrite caused a measurable increase of 2 mm or more in sphincter diameter in nine patients with idiopathic achalasia. The amyl nitrite test may be a useful method for distinguishing patients with pseudoachalasia from those with idiopathic achalasia.

Adult↗
PubMed1985

Tachypnoeic response to amyl nitrite inhalation in the rabbit.

Intratracheal inhalation of amyl nitrite, a non-specific smooth muscle relaxant, in the pentobarbitone/urethane anaesthetized rabbit caused reductions in tidal volume and both inspiratory and expiratory times, without a preceding apnoea, that were independent of the associated hypotension and of reflex influences from the carotid sinus region but dependent on supra-abdominal vagal integrity. In artificially ventilated, paralyzed rabbits amyl nitrite caused a pronounced sensitization of pulmonary stretch receptors (PSRs) during the inflation phase, typically with a reduction in the level of activity during the deflation phase. The time course of the change in the pattern of PSR activity paralleled that of the tachypnoeic response. The sensitization of a small sample of rapidly adapting 'irritant' receptors was of a significantly shorter duration. A unitary analysis of non-myelinated vagal afferents was not attempted. The sensitization of these vagal afferents cannot be attributed to the smooth muscle relaxant properties of amyl nitrite since other relaxants (sodium nitrite, sodium nitroprusside, phentolamine) did not possess this capacity, and such properties would be expected to diminish their activities.

Afferent Pathways↗
PubMed1977

Action of Nitroglycerin and amyl nitrite in labile and essential hypertension: hemodynamic differences.

Seventeen patients with labile hypertension received nitroglycerin and 18 received amyl nitrite. Twelve patients with established essential hypertension received nitroglycerin and 12 received amyl nitrite. Nitroglycerin reduced the systolic and mean arterial pressures and cardiac output in both groups, but had no effect on diastolic pressure and total peripheral resistance. Amyl nitrite decreased systolic, diastolic, and mean arterial pressures and peripheral vascular resistance and increased heart rate and cardiac output in labile hypertensives. In established hypertensive patients, amyl nitrite decreased systolic, diastolic, and mean arterial pressures and cardiac output, and had little effect on peripheral vascular resistance. Nitroglycerin reduced arterial pressure in labile and established hypertensives through venodilation and peripheral venous pooling. Amyl nitrite and effects similar to nitroglycerin in established hypertensives; in labile hypertensives it reduced arterial pressure through arterial dilation and a decrease in peripheral vascular resistance.

Adult↗
PubMed1990

Use of Doppler echocardiography and amyl nitrite inhalation to characterize left ventricular outflow obstruction in hypertrophic cardiomyopathy.

The presence of left ventricular outflow tract obstruction (LVOTO) of either a resting or dynamic nature may have important therapeutic and prognostic implications in patients with hypertrophic cardiomyopathy (HCM). Doppler echocardiograms combined with amyl nitrite (Amyl) inhalation were performed in 333 consecutive patients referred for suspected HCM to diagnose and categorize the nature and severity of LVOTO. Hypertrophic cardiomyopathy was present by 2-D and M-mode criteria in 145/333 (44 percent) patients. Normal limits of resting and post-Amyl continuous wave Doppler peak left ventricular outflow tract velocities were established in 15 subjects with completely normal 2-D and Doppler echocardiograms. Based on these criteria, of the 145 patients with HCM, 63 (43 percent) were classified as having resting LVOTO, peak velocity 4.2 +/- 1.3 m/s. Among 82 patients with HCM without resting LVOTO, 47 (57 percent) received Amyl. Latent LVOTO was provoked in 25/47 (53 percent), peak post-Amyl velocity 4.5 +/- 1.2 m/s. The remaining 22 (47 percent) had nonobstructive HCM, as indicated by no significant increase in post-Amyl velocity. Among a total 62 subjects receiving Amyl, none experienced serious morbidity or mortality. Doppler echocardiography, in conjunction with Amyl inhalation in selected patients, is a useful noninvasive method to diagnose and categorize patients with HCM according to the nature and severity of LVOTO.

Aged↗
PubMed1978

Comparison of heart rate and blood pressure response to amyl nitrite, isoproterenol, and standing before and during acute beta-adrenergic blockade with intravenous propranolol.

Heart rate responses to three different procedures (amyl nitrite inhalation, standing up, and isoproterenol infusion), were studied before and during acute adrenergic beta blockade with intravenous propranolol in three normal and six hypertensive subjects. Propranolol decreased, but did not completely abolish, the heart rate increase produced by amyl nitrite and standing, probably because of vagal participation (withdrawal) in heart rate increase produced by baroreceptor hypotension (amyl nitrite) and on assuming the upright posture. Heart rate responses to amyl nitrite varied greatly from patient to patient (from 27 to 97%), but the drug proved to be the most potent stimulus for heart rate increase as a result of its marked hypotensive effect. However, this vasodilator-induced acute hypotension was well tolerated, and without deleterious hemodynamic consequences, despite the presence of beta blockade. Different degrees of correlation in heart rate increase were observed with the three procedures, reflecting probably the varying sympathetic-parasympathetic participation in reflex heart rate control. It is concluded that from the clinical stand point, neither amyl nitrite administration nor standing up can be used as a test to assess acurately the degree of beta blockade, because both procedures activate vagal withdrawal which increases heart rate regardless of the degree of beta blockade.

Adult↗
PubMed2000

Inhalation of amyl nitrite and the measurement of left ventricular outflow velocity: studies in normal, young adults.

Amyl nitrite inhalation is useful in the identification of patients with provocable left ventricular (LV) outflow tract obstruction. However, there are no prospective studies that assess the normal change in LV outflow velocity during this intervention. Eighteen normal subjects (mean age, 34+/-5 years; 9 men and 9 women) inhaled amyl nitrite during measurement of LV outflow velocity. Peak velocity increased from 109+/-16 cm/s to 144+/-24 cm/s (P<0.001). There were no significant gender differences in velocity measurements at baseline or at peak. Our study provides prospective data that may be useful when evaluating young adults for LV outflow tract obstruction with Doppler echocardiography during amyl nitrite inhalation.

Administration, Inhalation↗
PubMed1985

Diaphragmatic, thoracic and limb motor effects of amyl nitrite inhalation.

In the pentobarbitone/urethane anaesthetized rabbit and pentobarbitone anaesthetized cat intratracheal inhalation of amyl nitrite, a non-specific smooth muscle relaxant, caused a vagally dependent depression of patellar reflex and spontaneous (thermal shivering and external intercostal inspiratory) motor activities. A prolonged vagally-independent potentiation succeeded the initial inhibition. The potentiation of intercostal activity may account for the increase in tidal volume produced by amyl nitrite after vagotomy. The patellar reflex potentiation survived thoracolumbar spinal transection but could not be attributed to a direct facilitation of neuromuscular or muscular events. A correlation existed between the relative dependence of fusimotor support of a muscle and its susceptibility to the inhibitory and subsequent facilitatory affects of amyl nitrite inhalation. The diaphragm and interchondral muscles, essentially independent of the autogenetic facilitation provided by muscle spindles, demonstrated neither of these effects. Conversely, the intercostal muscles depend greatly on such facilitation, as do the pectoral and limb muscles during thermal shivering.

Amyl Nitrite↗
PubMed1989

Regional cerebral blood flow changes associated with amyl nitrite inhalation.

Regional cerebral blood flow (CBF), mood states and somatic symptoms were measured before and after inhalation of amyl nitrite in 10 physically healthy volunteers with a prior history of using volatile nitrites for recreational purposes. CBF was measured with the same technique, under identical laboratory conditions, in an equal number of normal volunteers. During CBF measurements, blood pressure, pulse rate, respiratory rate and end-tidal levels of carbon dioxide were monitored. The amyl nitrite group and the control group were compared on CBF, rating scale scores and physiological indices via analysis of variance. Amyl nitrite inhalation was associated with significant global increases in CBF, while the control group did not show any change. Pulse rate increase was the only physiological change associated with administration of the drug. Subjects who received the drug reported significant decrease in anger, fatigue and depression and increased palpitation, breathing difficulty, dizziness and headache. Changes in the rating scale scores, physiological indices, and somatic symptoms after amyl nitrite did not correlate with regional CBF change.

Administration, Inhalation↗
PubMed1977

Effects of amyl nitrite on phasic aortocoronary bypass graft blood velocity in man.

With the use of a Doppler flowmeter catheter, phasic instantaneous aortocoronary saphenous vein bypass graft blood velocity was continuously measured during the inhalation of amyl nitrite in 20 closed-chest conscious subjects. Administration of amyl nitrite augmented peak diastolic and systolic graft blood velocity within 10 seconds and maximal blood velocities were recorded between 8 and 60 seconds after inhalation. Control mean (+/- 1 S.D.) bypass graft blood velocity was 25 +/- 10 cm. per second and after amyl nitrite 46 +/- 14 cm. per second, resulting in an average 84 per cent rise of blood velocity. It is concluded that amyl nitrite increases aortocoronary bypass graft blood velocity, suggesting a possible enhancement of blood flow to the distal native circulation in patients so operated upon.

Adult↗
PubMed1991

Detection of coronary artery disease by vasodilator thallium imaging of the heart with amyl nitrite inhalation: a pilot study.

Thallium imaging of the heart using dipyridamole-induced coronary arteriolar vasodilation has proven to be an effective means of detecting significant coronary stenosis. However, intravenous dipyridamole has not yet been made available for general use. We therefore examined the feasibility of substituting amyl nitrite inhalation as an arteriolar vasodilator prior to thallium imaging. Seventeen patients, all of whom had catheterization-proven coronary stenosis, inhaled amyl nitrite for 2-5 min. Thallium was injected after 45-60 s of inhalation. Completion of inhalation was followed immediately by planar imaging. Of 6 patients who inhaled amyl nitrite for at least 4 min, 5 had moderate or severe image defects on immediate scans which completely resolved on delayed scans. Only 3 of 11 who inhaled amyl nitrite for 2 min or less prior to scanning had similarly positive tests. Overall sensitivity for significant stenosis was 8 of 17 (47%). Inhalation was well tolerated with only one episode of angina and hypotension. We conclude that amyl nitrite inhalation for at least 4 min may offer an effective and readily available alternative to intravenous dipyridamole for vasodilator imaging of the heart.

Administration, Inhalation↗
PubMed1982

The effect of amyl nitrite on the mitral valve echocardiogram in presumably healthy young adults.

We analyzed the use of amyl nitrite as a provocative factor in the diagnosis of mitral valve prolapse in a population of healthy young adults. Sixty-five men and 11 women underwent continuous M-mode echocardiographic and phonocardiographic monitoring before, during and after the administration of inhaled amyl nitrite. All of the 76 subjects had normal baseline echocardiograms, and all had a satisfactory hemodynamic response to amyl nitrite. Mitral valve prolapse, defined by echocardiography and phonocardiography, was not provoked in any of the subjects. Therefore, we concluded that, although this technique may be difficult, significant false-positive results should not occur if adherence to strict diagnostic criteria takes place.

Adult↗
PubMed1982

Effects of amyl nitrite on left ventricular relaxation in patients with borderline hypertension.

The effects of systemic hypertension on left ventricular relaxation properties remain largely undefined. To assess such effects 22 normal volunteers and 15 patients with borderline hypertension were examined. The tangent to the echocardiographic left ventricular posterior wall endocardium was measured in diastole and was normalized for end-diastolic dimension to yield normalized velocity of relaxation. This velocity of relaxation was measured at rest and throughout inhalation of amyl nitrite. Mean value +/- standard deviation (SD) from rest to peak amyl nitrite effect for the normal group and for the patients with borderline hypertension was 3.3 +/- 0.6 leads to 7.2 +/- 1.1 and 3.0 +/- 0.8 leads to 4.4 +/- 1.1 s-1, respectively. All 22 persons in the normal group and 2 of the 15 patients with borderline hypertension attained normalized velocity of relaxation greater than 5.5 s-1 with administration of amyl nitrite. Multivariate analysis in the normal group identified heart rate, mean arterial pressure, and fractional shortening as the best predictors of normalized left ventricular relaxation velocity (r = 0.85; p less than 0.001). The increase in the normalized velocity of relaxation induced by amyl nitrite is blunted in patients with borderline hypertension. These changes in left ventricular relaxation identify early cardiac involvement and may prove clinically useful in hypertensive patients.

Adult↗
PubMed1975

Simultaneous echocardiographic phonocardiographic recordings at rest and during amyl nitrite administration in patients with mitral valve prolapse.

Simultaneous electrocardiograms, phonocardiograms, and echocardiograms were recorded in 21 patients with mitral valve prolapse. Four patients with holosystolic mitral valve prolapse on echocardiogram had smaller resting end-diastolic volumes than the remaining 17 patients with late systolic echocardiopraphy prolapse (p greater than 0.01). Thirteen of the 17 patients with late systolic prolapse had phonocardiograhically recorded auscultatory phenomena. The initial vibrations of the auscultatory phenomena occurred after the onset of echocardiographic prolapse, but prior to maximal echocardiographic mitral valve prolapse. Amyl nitrite was administered to all patients. Three of the 17 patients with late systolic prolapse developed holosystolic prolapse, while the remaining 14 retained the late systolic prolapse pattern during amyl nitrite inhalation. In these 14 patients, the onset of mitral prolapse occurred earlier in systole due to decrease in the duration of systole prior to onset of mitral valve prolapse (p greater than 0.001). This corresponded with the occurrence of auscultatory phenomena earlier in systole. Twelve patients had left ventricular volumes recorded during amyl nitrite inhalation and all showed a decrease in left ventricular volumes (greater than) 0.001). These findings confirm the temporal relationship of mitral valve prolapse and onset of auscultatory phenomena in these patients. It suggests that the movement of auscultatory phenomena earlier in systole during amyl nitrite inhalation is related to earlier prolapse of the mitral valve, and that a decrease in ventricular valume is a tenable explanation for the earlier onset of prolapse.

Administration, Intranasal↗