Acute effects of ethanol and acetaldehyde on blood pressure and heart rate in disulfiram-treated and control rats

Pharmacological Inhibition of Gasdermin D Suppresses Angiotensin II-Induced Experimental Abdominal Aortic Aneurysms

BACKGROUND

Gasdermin D, a molecule downstream of the nucleotide-binding oligomerization domain-like receptor family pyrin domain containing inflammasome, forms the membrane pore for the secretion of interleukin (IL)-1β and IL-18, and also mediates pyroptosis. This study was to explore the influence of treatment with disulfiram, a small molecule inhibitor to gasdermin D, on the formation and progression of experimental abdominal aortic aneurysms (AAA).

METHODS

AAAs were induced in 10-week-old male apolipoprotein E deficient mice by subcutaneous infusion of angiotensin II (1000 ng/min/kg body weight) for 28 days via osmotic minipumps. Three days prior to angiotensin II infusion, disulfiram (50 mg/kg) or an equal volume of saline as the vehicle control was administered daily via oral gavage. The influence on experimental AAAs was analyzed by serial measurements of aortic diameters via ultrasonography, grading AAA severity and histopathology at sacrifice. Serum IL-1β and IL-18 levels, systolic blood pressure, total cholesterol, and triglyceride were also measured. Additional experiments assayed the influences on the cell viability and IL-1β secretion of in vitro activated macrophages.

RESULTS

Disulfiram significantly reduced the enlargement, incidence, and severity of angiotensin II-induced experimental AAAs with attenuation of medial elastin breaks, mural macrophage accumulation, and systolic blood pressure. The AAA suppression was also associated with reduced systemic levels of IL-1β but not IL-18. However, disulfiram treatment had no impact on body weight gain and lipid levels in aneurysmal mice. Additionally, disulfiram treatment also markedly reduced the secretion of IL-1β from activated macrophages with a limited effect on cell viability in vitro.

CONCLUSIONS

Gasdermin D inhibition by disulfiram attenuated angiotensin II-induced experimental AAAs with reduced systemic IL-1β levels and in vitro activated macrophage IL-1β secretion. Our study suggests that pharmacological gasdermin D inhibition may have translational potential for limiting clinical AAA progression.

Effect Modification of Acetaldehyde Dehydrogenase 2 rs671 Polymorphism on the Association between Alcohol Intake and Blood Pressure: the Dong-gu Study

BACKGROUND

Elevated blood pressure is a major preventable cause of cardiovascular diseases. Alcohol consumption is a well-known risk factor of elevated blood pressure. The aldehyde dehydrogenase 2 (ALDH2) polymorphism is common in Eastern Asians, and inactive ALDH2 genotypes are associated with both avoiding alcohol consumption and aldehyde accumulation. Therefore, this study assessed the associations between alcohol consumption and hypertension and blood pressure according to the ALDH2 genotypes.

METHODS

This study consists of 8,526 participants in the Dong-gu Study. Multivariate logistic regression was used to calculate the odds ratio (OR) according to alcohol consumption after stratifying by gender and ALDH2 genotypes. Multivariate linear regression was performed to estimate the systolic blood pressure (SBP) and diastolic blood pressure (DBP) according to the amount of alcohol consumed.

RESULTS

In men, alcohol consumption was positively associated with both SBP and DBP in active ALDH2 carriers, but not in inactive ALDH2 carriers. In active ALDH2 carriers, compared to non-drinkers, the OR of hypertension was 1.16 (95% confidence interval [CI], 0.91-1.49) for < 1 drink/day, and 1.44 (95% CI, 1.15-1.80) for ≥ 1 drink/day in men. With each 1 drink/day increase, SBP and DBP increased by 3 and 1 mmHg in men, respectively. There was no significant association between ALDH2 genotypes and hypertension and blood pressure in women.

CONCLUSION

ALDH2 genotype modified the association between alcohol consumption and blood pressure in men. There was a positive relationship between alcohol consumption and blood pressure in active ALDH2 carriers, but no significant relationship in inactive ALDH2 carriers.

Targeting ALDH2 in Atherosclerosis: Molecular Mechanisms and Therapeutic Opportunities

Aldehyde dehydrogenase 2 (ALDH2) is an important member of the functional aldehyde dehydrogenases (ALDHs) family in human beings, playing a fundamental role in the detoxification of acetaldehyde and other aldehydes. In recent years, a number of researches have given attention to the association between ALDH2 and atherosclerosis, which provided insights on targeting ALDH2 for therapeutic intervention of atherosclerosis. In this review, these inspiring studies will be discussed, and the clinical implications and concerns will be expounded.

Delayed formation of hematomas with ethanol preconditioning in experimental intracerebral hemorrhage rats

Objective:

Spontaneous intracerebral hemorrhage (ICH) accounts for 10%–15% of all strokes and causes high mortality and morbidity. In the previous study, we demonstrated that ethanol could aggravate the severity of brain injury after ICH by increasing neuroinflammation and oxidative stress. In this study, we further investigate the acute effects of ethanol on brain injury within 24 h after ICH.

Materials and Methods:

Totally, 66 male Sprague-Dawley rats were assigned randomly into two groups: saline pretreatment before ICH (saline + ICH), and ethanol pretreatment before ICH (ethanol + ICH). Normal saline (10 mL/kg) or ethanol (3 g/kg, in 10 mL/kg normal saline) was administered intraperitoneally 1 h before induction of experimental ICH. Bacterial collagenase VII-S (0.23 U in 1.0 μL sterile saline) was injected into the right striatum to induce ICH in the rats. We evaluated the hematoma expansion, hemodynamic parameters (heart rate and blood pressure), activated partial thromboplastin time (aPTT), prothrombin time (PT), and striatal matrix metallopeptidase 9 (MMP-9) expressions at 3, 6, 9, and 24 h after ICH.

Results:

The ethanol + ICH group exhibited decreased hematoma at 3 h after ICH; nevertheless, there was a larger hematoma compared with the saline + ICH group at 9 and 24 h after ICH. The ethanol + ICH group had lower blood pressure at 3, 6, and 9 h post-ICH, but both groups maintained similar heart rates after ICH. There was no significant difference in the aPTT and PT between the two groups. Incremental ethanol concentrations had no influence on collagenase VII-S activity at 120 min in vitro. MMP-9 expression was upregulated in the right striata of the ethanol + ICH group, especially at 3 and 9 h after ICH.

Conclusion:

Ethanol delayed hematoma formation in the first 3 h due to a hypotensive effect; however, the accelerated growth of hematomas after 9 h may be a sequela of ethanol-induced MMP-9 activation.

Aldehyde dehydrogenase type 2 activation by adenosine and histamine inhibits ischemic norepinephrine release in cardiac sympathetic neurons: mediation by protein kinase Cε

During myocardial ischemia/reperfusion, lipid peroxidation leads to the formation of toxic aldehydes that contribute to ischemic dysfunction. Mitochondrial aldehyde dehydrogenase type 2 (ALDH2) alleviates ischemic heart damage and reperfusion arrhythmias via aldehyde detoxification. Because excessive norepinephrine release in the heart is a pivotal arrhythmogenic mechanism, we hypothesized that neuronal ALDH2 activation might diminish ischemic norepinephrine release. Incubation of cardiac sympathetic nerve endings with acetaldehyde, at concentrations achieved in myocardial ischemia, caused a concentration-dependent increase in norepinephrine release. A major increase in norepinephrine release also occurred when sympathetic nerve endings were incubated in hypoxic conditions. ALDH2 activation substantially reduced acetaldehyde- and hypoxia-induced norepinephrine release, an action prevented by inhibition of ALDH2 or protein kinase Cε (PKCε). Selective activation of G(i/o)-coupled adenosine A(1), A(3), or histamine H(3) receptors markedly inhibited both acetaldehyde- and hypoxia-induced norepinephrine release. These effects were also abolished by PKCε and/or ALDH2 inhibition. Moreover, A(1)-, A(3)-, or H(3)-receptor activation increased ALDH2 activity in a sympathetic neuron model (differentiated PC12 cells stably transfected with H(3) receptors). This action was prevented by the inhibition of PKCε and ALDH2. Our findings suggest the existence in sympathetic neurons of a protective pathway initiated by A(1)-, A(3)-, and H(3)-receptor activation by adenosine and histamine released in close proximity of these terminals. This pathway comprises the sequential activation of PKCε and ALDH2, culminating in aldehyde detoxification and inhibition of hypoxic norepinephrine release. Thus, pharmacological activation of PKCε and ALDH2 in cardiac sympathetic nerves may have significant protective effects by alleviating norepinephrine-induced life-threatening arrhythmias that characterize myocardial ischemia/reperfusion.

Influences of changes in calcium concentrations, cocaine and clonidine on the cardiac effect of acetaldehyde in rat isolated atria

1. Cardiovascular responses to acetaldehyde (AChO) were investigated in rat isolated atria. 2. Results show that two different doses of AChO (0.29 and 0.88 mM) induce positive inotropic effects on rat atria, and express Ca2+ dependence when analyzed at three external Ca2+ concentrations (0.6, 1.1, 2.2 mM). 3. Cocaine (3.5 and 35 microM) produced significant potentiation of the AChO-positive (0.29 and 0.88 mM) inotropic effect in 1.1 mM Ca2+ medium. 4. Clonidine (40 microM) increased the peak tension developed (PTD) induced by AChO (both 0.29 and 0.88 mM) only 1.1 mM Ca2+ medium. 5. It is suggested that the positive inotropic effect produced by AChO involves a Ca2(+)-dependent mechanism, which can be potentiated by the additional stimulation of alpha-adrenergic receptors.

Haemodynamic alterations in anaesthetized and acutely intoxicated newborn piglets

1. We investigated the haemodynamic alterations in 2-day old anaesthetized piglets after acute ethanol intoxication using the microsphere technique. 2. After ethanol infusion, mean arterial blood pressure (MABP) decreased by 6%, cardiac output (CO) decreased by 26%, heart rate (HR) increased by 20% and systemic vascular resistance (SVR) increased by 36%. 3. Arterial perfusion to the kidneys, gastrointestinal (GI) organs and carcass decreased by 39%, 34% and 26%, respectively. 4. In piglets pretreated with 4-methylpyrazole (4-MP), an alcohol dehydrogenase inhibitor, the decrease in MABP and increase in HR were not observed after ethanol infusion, but the reduction in CO and increase in SVR were maintained. 5. Arterial blood flow to the GI organs and carcass, but not the kidneys, remained at significantly reduced levels. 6. These observations indicate that ethanol can adversely affect CO and arterial perfusion to GI and musculoskeletal structures while metabolites of ethanol, such as acetaldehyde, affect MABP and HR. Therefore, the clinical effects observed after acute ethanol intoxication in neonates may vary with their rate of ethanol metabolism.

Effects of acetaldehyde on membrane potentials of sinus node pacemaker fibers

The experiments reported here were performed to characterize the effects of acetaldehyde on membrane potentials (MP) of sinus node subsidiary pacemaker fibers in the absence and presence of adrenergic and cholinergic blockade. Guinea pig sinoatrial preparations were superfused with Tyrode's solution at 37 degrees C while electrically stimulated at 5 Hz. Intracellular microelectrodes were used to record the MP of sinus node subsidiary pacemaker fibers. Acetaldehyde 3 x 10(-6) M and 3 x 10(-3) M had no effect on maximum diastolic potential (MDP), while 3 x 10(-5) M and 3 x 10(-2) M exerted a depolarizing effect on the MDP, without affecting the overshoot (OS). The fall in MDP was associated with a reduction in the amplitude of the action potential (AAP) and the maximum velocity of phase 0 (Vmax 0). The depressant effect of acetaldehyde on MDP was not abolished by adrenergic blockers or atropine. Concentrations of acetaldehyde between 3 x 10(-5) and 3 x 10(-2) M prolonged the action potential duration (APD). Acetaldehyde 3 x 10(-3) M did not affect MDP even in the presence of atropine or propranolol. The APD-prolonging effect of acetaldehyde was not abolished by adrenergic blockers. In summary, the actions of acetaldehyde on MDP and APD were independent of adrenergic and cholinergic mechanisms.

Cardiovascular effects of ethanol in anaesthetized, conscious and pithed rats

The influence of ethanol (2.0 g/kg p.o.) on heart rate and blood pressure in anaesthetized, conscious and pithed rats was studied. In anaesthetized rats we observed an increase in heart rate and a marked and very sudden decrease in blood pressure. In pithed rats blood pressure decreased more slowly than in anaesthetized and conscious animals and there were no changes in heart rate. These results show that the central nervous system may be responsible for the increase in heart rate and early phase of hypotension caused by acute ethanol administration. The slower decrease (up to 1 h) in blood pressure may be caused by central and different indirect peripheral mechanisms.

Kinetic disposition of ethanol in the neonatal piglet and hemodynamic effects in the presence and absence of 4-methylpyrazole

The hemodynamic effects of acute ethanol intoxication and the kinetic disposition of ethanol are reported for the first time in neonatal piglets under nitrous oxide anesthesia. Two hours after a single dose of ethanol (1.4 g/kg), blood pressure decreased from 76 +/- 4 to 71 +/- 4 mm Hg (p less than 0.05) and heart rate increased from 194 +/- 10 to 227 +/- 8 beats/min (p less than 0.05; means +/- SE). By 5 hr, blood pressure dropped to 67.5 +/- 4 mm Hg and heart rate increased to 239 +/- 8 beats/min. In piglets pretreated with 4-methylpyrazole, an alcohol dehydrogenase inhibitor, there was a transient increase in blood pressure (p less than 0.05) and a decrease in heart rate (p less than 0.05) immediately after the end of the ethanol infusion. However, the hemodynamic alterations observed 2 hr after ethanol treatment alone were prevented with 4-methylpyrazole. These findings indicate that ethanol metabolites play a significant role in hemodynamic alterations observed after acute ethanol intoxication. The mean ethanol metabolic rate derived from plasma data was 94 +/- 9 mg/liter/hr. This corresponded to an apparent Km of 68 +/- 3 mg/liter and a Vm of 123 +/- 11 mg/liter/hr. The Vd was 0.966 +/- 0.031 liter/kg. The metabolic rate for ethanol, derived from plasma data, correlated with in vitro alcohol dehydrogenase activity at pH 7.4 and 25 and 37 degrees C. The optimum pH for hepatic alcohol dehydrogenase activity was 9.9.

Effects of acetaldehyde on the automaticity of the guinea pig sinus node

The objective of this investigation was to characterize the effects of acetaldehyde (ACA) on sinus node automaticity (SNA). Guinea pig sinoatrial preparations superfused with Tyrode's solution at 37 degrees C were used. Intracellular microelectrodes were used to monitor SN rate (SNR). Acetaldehyde 3 X 10(-5) M had no effect on SNR, while 3 X 10(-3) M had a positive chronotropic action. The increase in SNR was associated with an increase in the slope of the slow diastolic depolarization (SDD) of subsidiary pacemaker fibers, with no change in the maximum diastolic potential (MDP). Acetaldehyde 3 X 10(-2) M exerted a biphasic effect: the SNR was enhanced and then depressed. Propranolol blocked the positive component of this chronotropic action. The negative component was not modified by propranolol, phentolamine, or atropine. It is concluded that ACA exerts both positive and negative chronotropic actions on the guinea pig sinus node. The positive component of this biphasic effect is mediated through a beta-adrenergic mechanism and it is associated with an increase in the SDD. The negative component is not due to alpha- or beta-adrenergic or muscarinic stimulation.

Comparative aspects of disulfiram and its metabolites in the disulfiram-ethanol reaction in the rat

Diethyldithiocarbamate-methyl ester (DDTC-Me), a metabolite of disulfiram, has been shown recently to produce a disulfiram-ethanol reaction (DER). Studies were carried out to compare the ethanol-sensitizing properties of DDTC-Me with those of disulfiram and diethyldithiocarbamate (DDTC) in the rat. All three drugs inhibited liver mitochondrial low Km aldehyde dehydrogenase (ALDH) in vivo, with maximal ALDH inhibition occurring 8 hr after drug administration. The onset of ALDH inhibition was most rapid after DDTC-Me administration. ALDH was inhibited approximately 50% 0.5 hr after DDTC-Me, whereas ALDH was inhibited only 5 and 10%, respectively, after disulfiram and DDTC. Not until 8 hr after drug treatment was ALDH inhibition the same for disulfiram, DDTC and DDTC-Me. The degree of ALDH inhibition from 8 to 172 hr after dosing was the same for all three drugs. An ethanol (1 g/kg, 20% v/v) challenge administered to rats treated with disulfiram (75 mg/kg), DDTC (114 mg/kg), or DDTC-Me (41.2 mg/kg) for 8 hr produced similar blood acetaldehyde/ethanol concentration-time profiles. In addition, all three agents produced a DER (hypotension, tachycardia). No DER occurred if ethanol was administered more than 24 hr after drug pretreatment. The hypotension associated with the DER correlated with the increased blood acetaldehyde but not blood ethanol. A threshold blood acetaldehyde of 110 microM appeared to be required for hypotension to occur, and this was related to ALDH inhibition of approximately 40%. The tachycardia associated with the DER correlated more with blood ethanol. After DDTC-Me administration, no disulfiram or DDTC could be detected in the plasma. Furthermore, no DDTC-Me was found in the plasma 8 hr after DDTC-Me administration, suggesting that no correlation exists between the DER and plasma concentration of DDTC-Me and most likely disulfiram. These data suggest that the alcohol-sensitizing properties of DDTC-Me are similar to those observed with disulfiram and DDTC. Since DDTC-Me is an active metabolite and more potent than disulfiram and DDTC in producing a DER, disulfiram metabolism is an important consideration in the disulfiram-ethanol reaction.

The effect of chronic alcohol inhalation on blood pressure and the pressor response to noradrenaline and the thromboxane-mimic U46619

Rats were exposed to alcohol vapor for 6 days and the mean blood ethanol concentration (BEC) was obtained for each subject. Blood pressure and its reactivity to noradrenaline and a thromboxane-mimic U46619 were directly measured on day 6 via a catheter implanted in the tail artery of normal and ethanol-treated animals. The mean BEC for each subject correlated with mean arterial blood pressure (MAP); an increase in BEC was associated with a decrease in MAP (p less than 0.02). The mean MAP of subjects with BEC less than 168 mg% was 8% higher than normal (not significant), whereas, the mean MAP of subjects with BEC greater than 182 mg% decreased 27 +/- 4% (p less than 0.01). Conversely, the pressor response to U46619 was markedly enhanced (p less than 0.005) in rats with mean BEC greater than 182 mg% at all doses investigated (12.5-3200 ng per rat). Increases in the pressor response to noradrenaline in ethanol-treated rats were significant only when maximally stimulated by 400 and 800 ng doses (p less than 0.03). A 3-fold increase in sensitivity for U46619 was seen in subjects with high mean BEC, however, sensitivity for noradrenaline did not significantly change. Vasoreactivity was not effected in rats with mean BEC less than 168 mg%. These data demonstrate that a moderate mean BEC for 6 days induces a tendency towards a mild hypertension, whereas, high mean BEC induces marked hypotension which is associated with hyperreactivity. Long-term exposure to high blood ethanol concentrations may predispose the alcohol-dependent rats to hypertensive disease and vasospastic disorders, at least partially, as a result of enhanced sensitivity to prostaglandins such as thromboxane.

Cardiorespiratory inhibitory reflex induced by intravenous administration of acetaldehyde in rats

In urethane anesthetized rats, intravenous administration of a bolus of acetaldehyde (diluted 50 times its volume in Ringer Locke solution) induced after a latency of about 1 second, a triple reflex response characterized by transient bradycardia, hypotension and apnea. Intensity of both bradycardia (r = -0.78) and hypotension (r = -0.74) were dose dependent (p less than 0.001). The triple response was blocked by vagotomy. Atropine and hexamethonium blocked bradycardia and hypotension and pretreatment of rats with reserpine (0.5 mg/100 g b.wt., IP) did not change the magnitude of the reflex response. The bolus effect was discarded by injecting the same volume of Ringer Locke solution in control test experiments. Administration of acetaldehyde directly into the left ventricle induced neither bradycardia nor hypotension, thus discarding a Bezold-Jarish reflex response. Administration of acetaldehyde directly into the right ventricle induced an increase in reflex bradycardia, hypotension and apnea with a shorter latency as compared to the intravenous route. The results suggest that the response induced by acetaldehyde is mediated by a reflex increase in vagal tone and probably is initiated in pulmonary vagal afferent fibers associated with the pulmonary J receptors.

Disulfiram-ethanol reaction in the rat. 1. Blood alcohol, acetaldehyde, and liver aldehyde dehydrogenase relationships

Studies were carried out to determine whether the disulfiram-ethanol reaction (DER) in the rat could be correlated with blood acetaldehyde, ethanol, and liver aldehyde dehydrogenase (ALDH) inhibition. Both hypothermia and hypotension were used as indices of the DER. Female Sprague-Dawley rats were given disulfiram (DSF) (100 mg/kg, i.p.) and low and high liver ALDH determined. No effect on high Km ALDH was found. Inhibition of low Km ALDH was dependent on DSF pretreatment time, with significant inhibition observed at 6, 8, and 12 hr following DSF. In rats receiving ethanol only, maximal blood ethanol was reached within 120 min. Blood acetaldehyde was almost undetectable. No change in rat core temperature was observed. In rats pretreated with DSF (100 mg/kg, i.p.) 8 hr before ethanol challenge (1 g/kg, i.p.), a marked increase in blood acetaldehyde was found and remained elevated throughout the temperature and blood pressure monitoring period. Blood ethanol reached a maximum within 90 min and then declined. Maximal hypothermia and hypotension occurred 120 min after ethanol. The administration of the dopamine receptor blocker pimozide (0.5 mg/kg, i.p.) 60 min before ethanol challenge, attenuated the hypothermia and hypotension. Pimozide was effective when given either 60 min before ethanol or 30 min after ethanol. The onset and duration of hypothermia and hypotension during the DER appears to follow the rise and fall of blood ethanol but not blood acetaldehyde.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of disulfiram on the oxidation of benzaldehyde and acetaldehyde in rat liver

The in vitro oxidation of benzaldehyde and acetaldehyde was studied in liver samples from disulfiram-treated and control rats. With 25 microM substrate, both cytosol and mitochondria appeared to make a nearly equal contribution to the oxidation of benzaldehyde, whereas ca. 90% of acetaldehyde oxidation occurred in mitochondria. When the Km values for benzaldehyde with aldehyde dehydrogenase (ALDH) were determined, two Km values (3 and 120 microM) were obtained with mitochondria, but only a single Km value (25 microM) was obtained with the cytosolic fraction. The relatively high Km (2.9 mM) found with microsomes makes it unlikely that microsomes are important in the oxidation of benzaldehyde. In intact mitochondria, with 200 microM acetaldehyde or benzaldehyde the matrix space enzyme accounted for 77 and 62%, respectively, of the total ALDH activity. When the activity was determined in a mixture containing both substrates, the activity was found not to be additive, indicating that both substrates are oxidized by the same matrix space enzyme. With subcellular fractions, from livers of disulfiram-treated and control rats, a greater degree of inhibition of ALDH was obtained when acetaldehyde was a substrate compared to that with benzaldehyde in cytosol and mitochondria. Microsomal ALDH was not inhibited by disulfiram. In liver slices from rats given disulfiram, a statistically significant inhibition was found when either 25 or 250 microM acetaldehyde was used (46 and 33%). With benzaldehyde, a significant inhibition (24%) was observed only with the lower substrate concentration. Finding that both mitochondrial fractions and slices were less inhibited at the higher substrate concentration implies that the high Km enzyme is not inhibited. It can be concluded that, in rat, disulfiram inhibiting liver ALDH not only affects oxidation of acetaldehyde, but also that of benzaldehyde.