Beneficial vs. detrimental actions of ethanol on heart and coronary vascular muscle: roles of Mg2+ and Ca2+

Ethanol enhances endothelial ionic currents and nitric oxide release via intermediate-conductance calcium-activated potassium channel

AIMS

Ethanol is known to induce NO release and coronary vasorelaxation. Evidence suggests that K⁺ channels, especially a Ca²⁺-activated K⁺ channel (K_Ca), may regulate endothelial NO production. We aimed to investigate the ethanol effect on K⁺ currents in human coronary artery endothelial cells (HCAECs), identify the K⁺ channel type/subtype and signaling pathway involved, and demonstrate the relevance to ethanol-induced NO release.

MAIN METHODS

Ionic currents of cultured HCAECs were studied using whole-cell patch clamp technique. NO production were measured using the fluorescent probe, 2,3-diaminonaphthalene.

KEY FINDINGS

We found that ethanol significantly potentiated HCAEC current (maximal increase to 155.68 ± 18.93%, 20 mM ethanol, +80 mV; mean ± SEM, n = 9). Ethanol-induced current was significantly inhibited by blockers of IK_Ca or SK_Ca (intermediate- or small-conductance K_Ca), but not by blocking other K⁺ channels. When other known HCAEC channels were inhibited except IK_Ca, 20 mM ethanol significantly increased IK_Ca current to 198 ± 25.11% (n = 6), but it could not enhance SK_Ca current that was similarly isolated. Moreover, ethanol-induced NO release was prevented by blocking IK_Ca channel, adenosine A_2A receptor (A_2AR), G_s protein, or protein kinase A (PKA).

SIGNIFICANCE

This study was the first to demonstrate that acute ethanol exposure could activate endothelial IK_Ca channel, via A_2AR-G_s-PKA signaling, leading to increased whole-cell current and NO release, which could be an important mechanism underlying ethanol-induced NO release and vasodilation.

Alcohol-Mediated Organ Damages: Heart and Brain

Alcohol is one of the most commonly abused substances in the United States. Chronic consumption of ethanol has been responsible for numerous chronic diseases and conditions globally. The underlying mechanism of liver injury has been studied in depth, however, far fewer studies have examined other organs especially the heart and the central nervous system (CNS). The authors conducted a narrative review on the relationship of alcohol with heart disease and dementia. With that in mind, a complex relationship between inflammation and cardiovascular disease and dementia has been long proposed but inflammatory biomarkers have gained more attention lately. In this review we examine some of the consequences of the altered cytokine regulation that occurs in alcoholics in organs other than the liver. The article reviews the potential role of inflammatory markers such as TNF-α in predicting dementia and/or cardiovascular disease. It was found that TNF-α could promote and accelerate local inflammation and damage through autocrine/paracrine mechanisms. Unraveling the mechanisms linking chronic alcohol consumption with proinflammatory cytokine production and subsequent inflammatory signaling pathways activation in the heart and CNS, is essential to improve our understanding of the disease and hopefully facilitate the development of new remedies.

Acute alcohol modulates cardiac function as PI3K/Akt regulates oxidative stress

BACKGROUND

Clinical manifestations of alcohol abuse on the cardiac muscle include defective contractility with the development of heart failure. Interestingly, low alcohol consumption has been associated with reduced risk of cardiovascular disease. Although several hypotheses have been postulated for alcoholic cardiomyopathy and for the low-dose beneficial cardiovascular effects, the precise mechanisms and mediators remain largely undefined. We hypothesize that modulation of oxidative stress by PI3K/Akt plays a key role in the cardiac functional outcome to acute alcohol exposure.

METHODS

Thus, acutely exposed rat cardiac tissue and cardiocytes to low (LA: 5 mM), moderate (MA: 25 mM), and high (HA: 100 mM) alcohol were assessed for markers of oxidative stress in the presence and absence of PI3K/Akt activators (IGF-1 0.1 μM or constitutively active PI3K: Ad.BD110 transfection) or inhibitor (LY294002 1 μM or Akt-negative construct Ad.Akt(K179M) transfection).

RESULTS

Acute LA reduced Akt, superoxide dismutase (SOD-3) and NFκB, ERK1, and p38 MAPK gene expression. Acute HA only increased that of SOD-3 and NFκB. These effects were generally inhibited by Ad.Akt(K179M) and enhanced with Ad.BD110 transfection. In parallel, LA reduced but HA enhanced Akt activity, which was reversed by IGF-1 and inhibited by Ad.Akt(K179M), respectively. Also, LA reduced caspase 3/7 activity and oxidative stress, while HA increased both. The former was blocked, while the latter effect was enhanced by Ad.Akt(K179M). The reverse was true with PI3K/Akt activation. This translated into reduced viability with HA, with no effect with LA. On the functional level, acute LA improved cardiac output and ejection fraction, mainly through increased stroke volume. This was accompanied with enhanced end-systolic pressure-volume relationship and preload recruitable stroke work. Opposite effect was recorded for HA. LA and HA in vivo functional effects were alleviated by LY and enhanced by IGF-1 treatment.

CONCLUSIONS

Acute LA and HA seem to oppositely affect cardiac function through modulation of oxidative stress where PI3K/Akt plays a pivotal role.

Alcohol and cardiovascular disease--modulation of vascular cell function

Alcohol is a commonly used drug worldwide. Epidemiological studies have identified alcohol consumption as a factor that may either positively or negatively influence many diseases including cardiovascular disease, certain cancers and dementia. Often there seems to be a differential effect of various drinking patterns, with frequent moderate consumption of alcohol being salutary and binge drinking or chronic abuse being deleterious to one’s health. A better understanding of the cellular and molecular mechanisms mediating the many effects of alcohol consumption is beginning to emerge, as well as a clearer picture as to whether these effects are due to the direct actions of alcohol itself, or caused in part by its metabolites, e.g., acetaldehyde, or by incidental components present in the alcoholic beverage (e.g., polyphenols in red wine). This review will discuss evidence to date as to how alcohol (ethanol) might affect atherosclerosis that underlies cardiovascular and cerebrovascular disease, and the putative mechanisms involved, focusing on vascular endothelial and smooth muscle cell effects.

Antiarrhythmic properties of acetaminophen in the dog

Mongrel dogs bred for research and weighing 25 +/- 3 kg were used to test the hypothesis that acetaminophen has antiar-rhythmic properties. Only ventricular arrhythmias defined by the Lambeth Conventions were investigated. Dogs were exposed either to 60 mins of regional myocardial ischemia followed by 180 mins of reperfusion (n = 14) or were administered a high dose of ouabain (n = 14). Both groups of 14 dogs were further divided into vehicle and acetaminophen treatment groups (n = 7 in each). During selected 10-min intervals, we recorded the numbers of ventricular premature beats, ventricular salvos, ventricular bigeminy, ventricular tachycardia (nonsustained and sustained), and we recorded the heart rate, systemic arterial blood pressure, and left ventricular function. Neither heart rate nor the number of ventricular arrhythmias differed significantly under baseline conditions. Conversely, the combined average number of ventricular ectopic beats during ischemia and reperfusion was significantly less in the presence of acetaminophen (28 +/- 4 vs. 6 +/- 1; P < 0.05). Similarly, percent ectopy during reperfusion in vehicle- and acetaminophen-treated dogs was 1.4 +/- 0.4 and 0.4 +/- 0.2, respectively (P < 0.05). The number of all ventricular ectopic beats except ventricular salvos was also significantly reduced in the presence of acetaminophen. Similar results were obtained with ouabain. Our results reveal that systemic administration of a therapeutic dose of acetaminophen has previously unreported antiarrhythmic effects in the dog.

Lower limb atherosclerotic disease causes various deteriorations of patients’ health-related quality of life

BACKGROUND

Lower limb atherosclerotic disease (LLAD) is a worldwide health problem. Approximately 100,000 Finns have LLAD. Currently, a large number of health-related quality of life (HRQoL) studies are available, but we still have scant comprehensive information of HRQoL of patients with LLAD.

OBJECTIVES

The aim was to describe the HRQoL of women and men with LLAD in relation to the age- and sex-matched general population. In addition, the purpose was to study which demographic and relevant clinical and psychologic factors are connected with HRQoL of patients with LLAD.

METHODS

Patients with LLAD (N = 180, 62 women and 118 men) were recruited to participate in this study in the Clinic of Surgery, Oulu University Hospital, from 2001 to 2004. The control sample consisted of an age- and sex-matched general population (N = 2126; 1081 women and 1045 men). The HRQoL of the women and men with LLAD was evaluated using the Nottingham Health Profile (NHP) instrument, in relation to an age- and sex-matched general population (N = 2126) as well as demographic and relevant clinical and psychologic factors.

RESULTS

The HRQoL of men was significantly (P < .05) poorer on all dimensions of the NHP instrument in the age groups 55 to 74 years. HRQoL was also clearly affected in the youngest age group of men on the dimensions of pain (P < .05) and mobility (P < .05) and further in the oldest age group on the dimension of energy (P < .05). The HRQoL of women with LLAD was only significantly poorer (P < .05) on the dimension of pain in the age group of 65 to 74 years than the HRQoL of age-matched Finnish women. The most emphasized relationships between poor HRQoL and the demographic, relevant clinical and psychologic factors were male sex, lack of exercise, retirement, a short painless walking distance, other atherosclerotic disease, poor subjective health status, problems with ability to cope at home, problems with the treatment of illness, and sex life. Male patients with LLAD had poorer HRQoL than the corresponding female patients on the dimensions of energy (P = .023), emotional reaction (P = .050), social isolation (P = .028), and NHP total score (P = .023). Those who did not exercise regularly had poorer HRQoL on the dimensions of energy (P = .005), pain (P = .049), emotional reaction (P = .007), social isolation (P = .001), and physical mobility (P = .028) than those who did exercise regularly.

CONCLUSIONS

The HRQoL of middle-aged men was significantly poorer than that of controls. Male sex, retirement, asymptomatic walking distance, other atherosclerotic disease, lack of exercise, and feeling incapable of performing daily activities are important causes of impaired HRQoL. Health care professionals should pay extra attention to the development of rehabilitation programs aimed at preventing patients with LLAD from experiencing a myriad of problems.

Effects of alcohol on intracellular pH regulators and electromechanical parameters in human myocardium

BACKGROUND

Disturbances in intracellular pH (pHi) of the heart can trigger major changes in the strength and rhythm of the heartbeat. It is well known that two extruders, Na+/H+ exchange (NHE) and Na+/HCO3- symporter (NHS), and a monocarboxylic acid transporter (MCT) are involved in acid-equivalent extruding in the human heart. Drinking alcohol has been proven to affect blood pressure and heart contractility and, sometimes, causes cardiac arrhythmia. To assess the effects of alcohol on pHi regulators and electromechanical parameters, various concentrations of alcohol were superfused into human myocardium in the present study.

METHODS

Human atrial myocardium was obtained from hearts of patients undergoing corrective cardiac surgery. Institutional rules for the protection of human subjects were observed. In the whole study, pHi was measured by an epifluorescent, ratiometric microspectrofluorimetry technique with the dye BCECF, while electrophysiological experiments were performed by traditional micropipette. NHE and NHS activities were measured after pHi recovery from intracellular acidosis induced by NH4Cl prepulse, while MCT activity was measured by a lactate adding/removing technique.

RESULTS

In pHi experiments, we demonstrated that alcohol could induce a biphasic, concentration-dependent (30-1000 mM) pHi change (i.e., alkalosis after acidosis) in human atrium in HEPES-buffered Tyrode solution. To a smaller extent, similar results were found when the superfusate was replaced by HCO3- -buffered Tyrode solution. NHE activity was increased by a moderate concentration of alcohol (30 mM), while it was inhibited in a concentration-dependent manner by higher concentrations of alcohol (>100 mM). On the contrary, 30-1000 mM alcohol increased the activity of NHS in a concentration-dependent manner. Surprisingly, MCT activity was not affected by alcohol. In electromechanical experiments, we found that alcohol (30-1000 mM) had a notable concentration-dependent inhibitory effect on the contractile force, while higher concentrations of alcohol (>100 mM) decreased the action potential amplitude, upstroke velocity, duration of repolarization, and force of contractions in a concentration-dependent way. All these alcohol-induced pHi changes and electromechanical inhibitions were reversible.

CONCLUSIONS

To our knowledge, this study provides the first evidence that alcohol can affect pHi in human myocardial tissue by changing the activity of acid extruders (i.e., NHE and NHS).

Mitochondria play a critical role in cardioprotection

BACKGROUND

There is increasing evidence documenting the capacity of myocardial cells exposed to a variety of insults to mount a cardioprotective response. Although this cardioprotection has been most well characterized with respect to ischemic preconditioning, other chemical and metabolic stressors have been shown to share features of the ischemic preconditioning model, including the involvement of mitochondria in the triggering, signaling, and mediation of the cardioprotective response.

METHODS

In this article, we review the evidence showing that mitochondria play a critical role in cardioprotection from multiple (often interrelated) standpoints: its primary function in producing the cellular bioenergetic supply, its control over events in apoptosis, its contribution to myocardial signal transducing processes, and its role in producing reactive oxidative species and in providing an appropriate antioxidant response to a variety of cellular insults.

CONCLUSIONS

Although our understanding of cytoprotection has increased substantially within the last few years, the mechanisms mediating mitochondrial resistance to insults leading to cardiac protection remain to be fully delineated, and represents a significant approach in the clinical treatment of heart disease.

Ethanol sensitivity of BK(Ca) channels from arterial smooth muscle does not require the presence of the beta 1-subunit

Ethanol inhibition of large-conductance, Ca(2+)-activated K(+) (BK(Ca)) channels in aortic myocytes may contribute to the direct contraction of aortic smooth muscle produced by acute alcohol exposure. In this tissue, BK(Ca) channels consist of pore-forming (bslo) and modulatory (beta) subunits. Here, modulation of aortic myocyte BK(Ca) channels by acute alcohol was explored by expressing bslo subunits in Xenopus oocytes, in the absence and presence of beta(1)-subunits, and studying channel responses to clinically relevant concentrations of ethanol in excised membrane patches. Overall, average values of bslo channel activity (NP(o), with N = no. of channels present in the patch; P(o) = probability of a single channel being open) in response to ethanol (3-200 mM) mildly decrease when compared with pre-ethanol, isosmotic controls. However, channel responses show qualitative heterogeneity at all ethanol concentrations. In the majority of patches (42/71 patches, i.e., 59%), a reversible reduction in NP(o) is observed. In this subset, the maximal effect is obtained with 100 mM ethanol, at which NP(o) reaches 46.2 +/- 9% of control. The presence of beta(1)-subunits, which determines channel sensitivity to dihydrosoyaponin-I and 17beta-estradiol, fails to modify ethanol action on bslo channels. Ethanol inhibition of bslo channels results from a marked increase in the mean closed time. Although the voltage dependence of gating remains unaffected, the apparent effectiveness of Ca(2+) to gate the channel is decreased by ethanol. These changes occur without modifications of channel conduction. In conclusion, a new molecular mechanism that may contribute to ethanol-induced aortic smooth muscle contraction has been identified and characterized: a functional interaction between ethanol and the bslo subunit and/or its lipid microenvironment, which leads to a decrease in BK(Ca) channel activity.

Ethanol reduces cardiac myocyte function through activation of the nitric oxide-cyclic GMP pathway

We tested the hypothesis that low-dose ethanol would reduce cardiac myocyte function through increased production in the nitric oxide/cyclic GMP signal transduction pathway, rather than reduced degradation. Ventricular myocytes were isolated from the hearts of 9 rabbits. Myocyte function was studied using a video-edge detector and cyclic GMP levels were measured by radioimmunoassay. Cells were administered 5 and 10 mmol/l ethanol alone or after 10(-6) mol/l N(G)-nitro-L-arginine methyl ester (L-NAME, nitric oxide synthase inhibitor), 10(-6) mol/l 1H-[1,2,4]oxadiazolo[4,3a]quinoxalin-1-one (ODQ, soluble guanylyl cyclase inhibitor) or 10(-5) mol/l zaprinast (cyclic GMP phosphodiesterase inhibitor). Ethanol (10 mmol/l) significantly decreased percent shortening from 10.0 +/- 0.9 to 6.0 +/- 0.2%. Similar decrements occurred in the maximum rate of shortening and relaxation. After L-NAME or ODQ, the decrements in percent shortening, maximum rate of shortening and relaxation caused by ethanol were not significant. After zaprinast, ethanol significantly decreased the maximum rate of shortening and relaxation and percent shortening to 4.3 +/- 0.5. Ethanol (10 mmol/l) significantly increased cyclic GMP from 403 +/- 121 to 529 +/- 128 fmol/10(5) myocytes. Both L-NAME and ODQ lowered cyclic GMP, and ethanol did not affect cyclic GMP after either. Zaprinast raised cyclic GMP, as did its combination with 10 mmol/l ethanol (653 +/- 120). Thus, ethanol both reduced myocyte function and increased cyclic GMP. Blocking nitric oxide production or guanylyl cyclase activity prevent these effects of ethanol, while blocking cyclic GMP degradation did not. This suggests that ethanol acts as a nitric oxide stimulator in ventricular myocytes leading to reduced function and increased cyclic GMP.

[Moderate alcohol consumption and cardiovascular diseases]

While excessive ethanol consumption can result in higher rate of morbidity and mortality resulting from several diseases including cancer and cirrhosis, epidemiological studies suggest that moderate alcohol ingestion reduces the risk of cardiovascular diseases. However, the precise mechanisms by which moderate alcohol consumption protects against coronary heart disease (CHD) is not fully understood. Epidemiological studies suggest that alcohol consumption influences several risk factors for CHD including blood pressure, plasma cholesterol levels, platelet function, and fibrinolytic parameters, preventing both vascular thrombosis and occlusion. Turning to molecular and cellular levels, ethanol has been shown to act on several signal transduction mechanisms involve in the inhibition of smooth muscle cells proliferation and migration and in the activation of the release of vasoactive factors from vascular cells such as nitric oxide (NO). The latter is of importance since NO has been shown to possess antioxidant, antiaggregant properties, to regulate vascular tone and to inhibit both proliferation of smooth muscle cells and adhesion of leukocytes. Altogether, the above mentioned beneficial properties of moderate concentration of ethanol might help to explain the cardio- and vascular protection induced by ethanol. This review compels several bibliographic data concerning the cardiovascular effect of moderate alcohol consumption.

Ethanol-induced reduction in myocardial oxygen consumption can be attenuated by inhibiting guanylyl cyclase

We tested the hypothesis that low-dose ethanol-induced reductions in myocardial metabolism were related to increased cyclic guanosine monophosphate (GMP). Anesthetized open chest rabbits were divided into four groups: control (Ringers lactate and vehicle), ETOH (250 mg/kg i.v. ethanol and vehicle), ODQ (Ringers lactate and 1 H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, ODQ 10(-4) M ), and ETOH-ODQ (ethanol and ODQ). ODQ, a soluble guanylyl cyclase inhibitor, or vehicle was applied topically to the epicardium for 15 min, while either Ringers lactate or ethanol was administered intravenously. Oxygen consumption (VO2 ) in both the subepicardium (EPI) and subendocardium (ENDO) was determined from coronary blood flow (radioactive microspheres) and O2 extraction (microspectrophotometry). Cyclic GMP was determined by radioimmunoassay. ETOH significantly decreased VO2 in the subepicardium (9.2 +/- 1.0-5.6 +/- 0.7 ml O2 /min/100 g) and subendocardium (9.7 +/- 0.8-7.1 +/- 0.8) and increased cyclic GMP in the subepicardium (10.2 +/- 1.7-13.8 +/- 0.8 pmol/g) and subendocardium (11.0 +/- 0.5-13.7 +/- 0.9). With ODQ, there was no significant change in the subepicardial (9.5 +/- 1.3) or subendocardial (9.0 +/- 0.9) VO2. However, ODQ caused a significant increase in both wall thickening (12.9 +/- 0.9-17.2 +/- 1.2%) and maximal rate of change in wall thickness (10.8 +/- 0.9-16.3 +/- 1.9 mm/s) and decreased subepicardium (8.3 +/- 1.3) and subendocardium (7.8 +/- 1.2) cyclic GMP. The ETOH-ODQ group had cyclic GMP (subepicardium 9.0 +/- 1.8, subendocardium 8.6 +/- 2.4) and VO2 (subepicardium 7.9 +/- 0.5, subendocardium 8.4 +/- 0.4) values similar to control. Thus, the ethanol-induced rise in cyclic GMP was associated with a decrease in myocardial O2 consumption. When this rise was blocked with a soluble guanylyl cyclase inhibitor, the reduction in metabolic demand was also eliminated. This demonstrated that the alcohol-induced reduction in myocardial metabolism was related to increased cyclic GMP and suggests a novel mechanism for the effect of ethanol.

Magnesium. An update on physiological, clinical and analytical aspects

There is an increased interest in the role of magnesium ions in clinical medicine, nutrition and physiology. The characteristics of the binding of magnesium and calcium ions to various components, macromolecules and biological membranes are described. Magnesium affects many cellular functions, including transport of potassium and calcium ions, and modulates signal transduction, energy metabolism and cell proliferation. The mechanism of cellular uptake and efflux of magnesium, its intracellular transport, intestinal absorption, renal excretion and the effect of hormones on these are reviewed. Magnesium deficiency is not uncommon among the general population: its intake has decreased over the years especially in the western world. The magnesium supplementation or intravenous infusion may be beneficial in various diseased states. Of special interest is the magnesium status in alcoholism, eclampsia, hypertension, atherosclerosis, cardiac diseases, diabetes, and asthma. The development of instrumentation for the assay of ionized magnesium is reviewed, as are the analytical procedures for total magnesium in blood and free magnesium in the cytosol. The improved procedures for the assay of different magnesium states are useful in understanding the role of magnesium in health and disease.

Interaction of alcohol and an alpha1-blocker on ambulatory blood pressure in patients with essential hypertension

Ingestion of alcohol acutely decreases vascular resistance and blood pressure (BP) with activation of the sympathetic nervous system in Orientals. Although alpha1-blockers are widely used in the treatment of hypertension, the possible interaction between alcohol and alpha1-blockers has not been clarified. We examined the effects of prazosin on the alcohol-induced BP changes in Japanese men with mild hypertension. Ten hypertensive patients (54 +/- 3 years, mean +/- SE) were given 1 mL/kg of alcohol or isocaloric control drink with a light meal in the evening before and 5 to 7 days after treatment with prazosin (1 mg three times daily). Ambulatory BP monitoring was carried out every 30 min for 24 h in each period using Colin ABPM-630. Blood samples were obtained before and 2 h after intake of alcohol or control drink. Before prazosin treatment, alcohol ingestion decreased BP for several hours with a significant reduction in average 24-h BP, whereas it increased heart rate, plasma norepinephrine, and plasma renin activity. Treatment with prazosin caused a significant decrease in 24-h BP (136.3 +/- 4.0/82.8 +/- 2.5 v 131.6 +/- 3.2/80.0 +/- 2.3 mm Hg). The alcohol-induced hypotension at 2-4 h after ingestion was enhanced by prazosin (-18.0 +/- 3.7/-11.8 +/- 2.7 v -24.4 +/- 4.9/-17.8 +/- 2.8 mm Hg, P < .05 for diastolic BP). These results suggested that inhibition of the sympathetic nervous system with alpha1-blockers accentuates alcohol-induced hypotension. Ingestion of alcohol may cause a marked BP reduction in hypertensive Orientals treated with alpha1-blockers.

Effects of propranolol on cardiovascular and neurohumoral actions of alcohol in hypertensive patients

Alcohol ingestion acutely lowers blood pressure (BP) with vasodilation and sympathetic activation in Oriental subjects. We examined the effects of beta blockade on cardiovascular and neurohumoral actions of alcohol in Japanese men with mild-to-moderate essential hypertension. Ten hypertensive patients (54+/-5 years, mean+/-SE) were given 1 ml/kg of alcohol or isocaloric control drink with a light meal in the evening before and 5-7 days after treatment with propranolol (20 mg three times daily). BP and heart rate (HR) were measured every 30 min for 24 h in each period. Blood sampling and echocardiographic examination were carried out before (17.00 h) and after (19.00 h) intake of alcohol or control drink, Before treatment, alcohol ingestion caused significant decreases in BP, total peripheral resistance and serum potassium concentration, while it increased heart rate (HR), cardiac output (CO), plasma norepinephrine and plasma renin activity (PRA). Treatment with propranolol significantly decreased BP and HR for 24 h. Propranolol and alcohol showed an additive depressor effect on night-time BP, and the alcohol-induced hypotension was similar before and after propranolol treatment. The alcohol-induced changes in HR, CO, PRA and serum potassium were significantly attenuated by propranolol. These results suggest that activation of the sympathetic nervous system plays a role in alcohol-induced cardiac stimulation, renin release and hypokalemia through beta receptors. Moderate doses of beta-blockers may not modify alcohol-induced BP reduction in Oriental subjects with hypertension.

Effects of protein kinase C inhibitors on ethanol-induced contractions in isolated rat aorta

The activation of intracellular contractile proteins induces vascular contraction mediated through signal transduction mechanisms. Protein kinase C (PKC) is involved in this signal transduction. The purpose of the present study was designed to investigate the role of PKC on EtOH-, KCl- and phorbol 12, 13-dibutyrate (PDBu)-induced contractions in isolated rat aorta through the use of several different PKC inhibitors. Prior exposure to staurosporine inhibited both EtOH- and KCl-induced contractions in a concentration-dependent manner. The EtOH-induced contractions were completely inhibited by staurosporine (5 x 10(-6) M) but complete inhibition of KCl-induced contractions was not observed. Staurosporine (10(-7) M) also significantly inhibited the contractile response to single doses of both EtOH and PDBu. Bisindolylmaleimide (10(-6) M) effectively inhibited contractile responses to both EtOH- and KCl, added cumulatively, and single doses of PDBu. Chelerythrine (10(-7) M) inhibited maximal EtOH-induced contractions. These results suggest that PKC activation plays an important role in the mechanism(s) involved in the contractile activation of rat aorta smooth muscle by EtOH, KCl and PDBu. However, further work is required to elucidate the precise molecular mechanism.

Exposure of piglet coronary arterial muscle cells to low alcohol results in elevation of intracellular free Ca2+: relevance to fetal alcohol syndrome

Chronic exposure of cultured piglet neonatal coronary arterial smooth muscle cells to low concentrations of ethanol (46-115 mg/dl) for 7 days resulted in concentration-dependent elevation in intracellular free Ca2+ ions ([Ca2+i); these rises (22-56%) in [Ca2+]i were not reversible upon short-term exposure to normal, Ca2(+)-containing physiological salt solution. These findings help to provide a rational basis for why ethanol can result in the well-known fetal alcohol syndrome, including cardiac defects and in-utero death.