Ethanol-induced hypocalcemia, hypermagnesemia and inhibition of the serum calcium-raising effect of parathyroid hormone in rats

Acamprosate reduces ethanol intake in the rat by a combined action of different drug components

Alcohol misuse accounts for a sizeable proportion of the global burden of disease, and Campral® (acamprosate; calcium-bis-(N-acetylhomotaurinate)) is widely used as relapse prevention therapy. The mechanism underlying its effect has in some studies been attributed to the calcium moiety and not to the N-acetylhomotaurine part of the compound. We recently suggested that the dopamine elevating effect of acamprosate is mediated both by N-acetylhomotaurine and calcium in a glycine receptor dependent manner. Here we aimed to explore, by means of in vivo microdialysis, if our previous study using local administration was functionally relevant and if systemic administration of the sodium salt of N-acetylhomotaurine (sodium acamprosate; 200 mg/kg, i.p.) enhanced the effects of calcium chloride (CaCl2; 73.5 mg/kg, i.p.) on nucleus accumbens (nAc) dopamine and/or taurine levels in male Wistar rats. In addition, we investigated the impact of regular acamprosate and the combination of CaCl2 and N-acetylhomotaurine on the alcohol deprivation effect (ADE). Finally, we assessed if N-acetylhomotaurine potentiates the ethanol-intake reducing effect of CaCl2 in a two-bottle choice voluntary ethanol consumption model followed by an ADE paradigm. Systemic administration of regular acamprosate, sodium acamprosate and CaCl2 all trended to increase nAc dopamine whereas the combination of CaCl2 and sodium acamprosate produced a significant increase. Sodium acamprosate elevated extracellular taurine levels without additional effects of CaCl2. Ethanol intake was significantly reduced by systemic administration of CaCl2 without additional effects of the combination of CaCl2 and sodium acamprosate. Both acamprosate and CaCl2 combined with sodium acamprosate blocked the ADE following acute treatment. The data presented suggest that CaCl2 and N-acetylhomotaurine act in concert on a neurochemical level, but calcium appears to have the predominant effect on ethanol intake.

Protein-bound calcium phosphate in uremic rat serum: a quantitative study

Protein-bound calcium (prCa) constitutes about 40% of serum total calcium, in which albumin is the most dominant protein. Given the chemical interaction between calcium and phosphate (Pi), the increased serum Pi in chronic kidney disease may cause changes in the composition and structure of the prCa fraction. Here, we report the phosphate binding on the protein-bound calcium in uremic rat serum. Using adenine-fed rats as a uremic model, we separated the calcium and phosphate fractions in rat serum by ultrafiltration, and found that the level of protein-bound phosphate (prPi) in the uremic serum was markedly higher than in control. The elevated prPi level was comparable to the prCa level, consistent with the presence of protein-bound calcium phosphate pr(Ca)_j-m(CaPi)_m. We then confirmed its presence by ex vivo X-ray absorption near-edge structure spectroscopy, revealing the discrete state of the calcium phosphate clusters associated with protein. Finally, in a quantitative investigation using Ca- and Pi-boosted serum, we discovered the threshold concentration for the Pi binding on prCa, and determined the binding constant. The threshold, while preventing Pi from binding to prCa in normal condition, allows the reaction to take place in hyperphosphatemia conditions. The protein-bound calcium phosphate could act as a link between the metabolism of serum proteins and the homeostasis of phosphate and calcium, and it deserves further investigation whether the molar ratio of (prPi/prCa)⋅100% may serve as a serum index of the vascular calcification status in chronic kidney disease.

Ex vivo detection of calcium phosphate and calcium carbonate in rat blood serum

The total calcium (tCa) in blood serum comprises free Ca²⁺ ions (fCa), protein-bound calcium (prCa), and complexed calcium by small anions (cCa). The cCa fraction, in addition to fCa, has been indicated to have some physiological activity. However, there is little evidence for the structure of its constituents. Here we report an ex vivo detection of the cCa constituents by synchrotron X-ray absorption near-edge structure spectroscopy. We collected the data directly on rat blood serum and, by making use of the reference samples, derived a spectrum that exhibits the features of cCa constituents. Among the features are those of the complexes of calcium phosphate and calcium carbonate. The detected complexes in the cCa fraction are mainly Ca(η²-HPO₄)(H₂O)₄ and Ca(η¹-HCO₃)(H₂O)₅⁺, in which HPO₄^2- and HCO₃^- serve as bidentate and unidentate ligands, respectively. The remained H₂O molecules on the coordination sphere of Ca²⁺ enable these complexes to behave partially like aquated Ca²⁺ ions in protein-binding. Besides, as the dominant part of prCa, albumin-bound calcium (albCa) exhibits a spectrum that closely resembles that of fCa, indicating weak interactions between the protein carboxyl groups and calcium. The weak-bound cCa and albCa, along with fCa and the relevant anions, compose a local chemical system that could play a role in maintaining the calcium level in blood.

Effects of Oral Calcium Dosage and Timing on Ethanol-Induced Sensitization of Locomotion in DBA/2 Mice

Ethanol (EtOH) dosage, frequency, and paired associative learning affect the risk of alcoholism. Recently, Spanagel et al. reported that acamprosate calcium (Acam Ca) prescribed for alcoholism exerts an anti-relapse effect via Ca. Ca is contained in foods, sometimes consumed with alcohol. Therefore, we investigated the association among oral Ca ingestion, EtOH-induced locomotor sensitization, and plasma Ca levels on how to consume Ca for moderate drinking. We used DBA/2 CrSlc mice, and CaCl₂ as water-soluble Ca salts. For pre-administration, elemental Ca (50, 75, 100, or 150 mg/kg, per os (p.o.)) or water for control was administered 1 h before EtOH (2 g/kg, 20 v/v (%) EtOH in saline) administration intraperitoneal (i.p.) for locomotor sensitization or for plasma Ca level changes. For post-administration, elemental Ca (100 mg/kg) was administered 1 h after EtOH. Moreover, we employed bepridil and the dopamine D1 antagonist, SCH-23390 to further examine the mechanism of EtOH-induced sensitization. The locomotor sensitization segmentalized for 300 s had two peaks (0-90 s and 180-300 s). Pre-administration of Ca (50, 75, and 100 mg/kg) significantly reduced the 0-90-s peak, selectively blocked by SCH-23390, but "non-dose dependently" as Ca 150 mg/kg did not have this effect. Bepridil blocked the suppressive effect of pre-administration of Ca (100 mg/kg). The effective pre-doses of Ca (50-100 mg/kg) maintained plasma Ca basal levels against EtOH-induced decrease of Ca. On the contrary, post-administration of Ca inversely led to significant promotion of sensitization of both locomotor peaks. Oral Ca intake had diverse effects on EtOH-induced sensitization depending on Ca dosage and timing.

Hypocalcaemia, alcohol drinking and viroimmune responses in ART recipients

Metabolic perturbations associated with HIV and antiretroviral therapies are widespread. Unfortunately, research has predominantly focused in cardiometabolic problems, neglecting other important areas. In fact, the immune-calcium-skeletal interface has been understudied despite its potential relevance in people living with HIV (PLWH). Using a case-control methodology, 200 PLWH receiving medical care were enrolled and stratified according to hazardous vs. non-hazardous alcohol intake (HAU vs. non-HAU) and calcium (Ca) levels by analyzing baseline data. The group was chosen to represent relatively "pure" HAU with minimal drug use and no psychiatric diagnoses. With these narrow parameters in place, we found evidence that HAU significantly increases TNF-α levels compared to Non-HAU (2.8 ± 0.6 vs. 1.9 ± 0.3 pg/ml, p = 0.05) and decreases blood Ca levels (9 ± 0.6 vs. 9.4 ± 0.5, p = 0.03). Our analyses also suggest that chronic inflammation, as indicated by increased TNF-α levels, is associated with hypocalcemia (hypoCa <8.6). Despite the limited prevalence of hypoCa, these findings are clinically significant given that hypoCA PLWH exhibited decreased CD4 (253 ± 224 vs. 417.7 ± 281, p = 0.02), B cells (147 ± 58 vs. 248 ± 151, p = 0.03) and NK cells (146.8 ± 90 vs. 229 ± 148, p = 0.008) and elevated CD8 (902.5 ± 438 vs. 699 ± 510, p = 0.09) compared to those with normal calcium. Furthermore, calcium effects on viral load were also evident with hypoCA exhibiting the highest loads (140,187 ± 111 vs. 35,622 ± 7770 HIV copies, p = 0.01). Multivariate analyses confirmed the significance of hypoCa in predicting viroimmune parameters. This paper provides the first evidence that hypoCa accounts for some of the variation in viroimmune measures in HAART recipients and suggests that hypoCa may be mediating alcohol's deleterious effects.

Effect of Chronic Ethanol Consumption on the Response of Parathyroid Hormone to Hypocalcemia in the Pregnant Rat

BACKGROUND

Chronic alcohol (ethanol) consumption during pregnancy results in maternal/fetal hypocalcemia, which may underlie some of ethanol's adverse effects on maternal and fetal bone, and fetal/neonatal health. Ethanol appears to alter the relationship between parathyroid hormone (PTH) and blood calcium (Ca) level, and PTH does not increase in response to ethanol-induced hypocalcemia. However, it is not known whether ethanol actually prevents PTH from responding, or whether the ability to regulate blood Ca is intact, but ethanol lowers the level of Ca maintained. The objective of this study was to determine whether chronic ethanol consumption impairs the ability of the pregnant female to increase PTH in response to acute hypocalcemia.

METHODS

Rats were fed isocaloric diets with ethanol (36% ethanol-derived calories, E group) or without ethanol [pair-fed (PF) and control (C) groups], before and throughout 21 days of gestation. On day 21 gestation, rats received an intraperitoneal injection of ethylene glycol-bis (beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) (300 or 500 mumol/kg body weight) or saline (saline group), or no injection (baseline group). Blood was collected from the baseline group, and at 30 or 60 minutes postinjection (saline and EGTA groups), and analyzed for ionized Ca (iCa), pH, and PTH.

RESULTS

Consistent with previous studies, ethanol consumption decreased blood iCa levels at baseline, but PTH levels did not differ among groups. Administration of EGTA significantly decreased blood iCa levels by 30 minutes, but ethanol did not prevent PTH from increasing in response to the hypocalcemia. In all diet groups, PTH levels were significantly increased by 30 minutes. Ethanol did, however, appear to decrease the maximum PTH level achievable in blood.

CONCLUSIONS

These data suggest that chronic ethanol consumption does not impair the ability of the pregnant rat to raise serum PTH levels in response to acute hypocalcemia, but ethanol's effect on maximal PTH secretion could impair the ability of the pregnant female to sustain high PTH levels in response to chronic hypocalcemia.

Ethanol administration results in a prolonged decrease in blood ionized calcium levels in the rat

Previous studies have shown that ethanol decreases the level of ionized calcium (iCa) in the blood, and appears to prevent a compensatory increase in parathyroid hormone level. We have shown, however, that the presence of ethanol interferes with the measurement of blood iCa by the most commonly used iCa analyzer. It is impossible to interpret ethanol-induced alterations in Ca-regulating hormone levels without accurate measurement of blood iCa, thus the purpose of this study was to determine if ethanol decreases blood iCa levels independent of methodological artifacts. The time course of ethanol's effect and the relationship between iCa and blood ethanol concentration (BEC) were also examined. Rats (n=22) received ethanol (1.5 or 3 g/kg body weight) or saline by intraperitoneal injection. Blood samples were obtained by tail nick at 0, 2, 6, 24, 48 h and 8 days postinjection, and analyzed for iCa, pH, and BEC. Blood iCa and pH were measured using the I-Stat Clinical Analyzer, whose performance is not affected by the presence of ethanol. Ethanol administration resulted in a decrease in blood iCa levels. The magnitude and time course of the decrease varied with dose of ethanol, being greater and more prolonged with the higher dose, and blood iCa levels were not fully recovered at 48 h postinjection. No significant relationship was found between individual iCa and BEC values. This study confirms that ethanol decreases blood iCa levels, independent of methodological artifacts. Prolonged disruptions in Ca homeostasis resulting from ethanol consumption could have implications for long-term bone health.

Ethanol interferes with the measurement of extracellular ionized calcium

BACKGROUND

Maintenance of extracellular calcium (Ca) concentration within narrow limits is critical for normal cell function and optimization of bone health. Ionized Ca (iCa), the form of Ca that is regulated, has been reported to vary inversely with blood alcohol concentration (BAC). The mechanism by which ethanol decreases blood iCa levels is unknown. However, one possible explanation is that it is, at least partially, a methodological artifact due to an effect of ethanol on the function of the ion selective electrode used to measure iCa. The purpose of this study was to determine if ethanol interferes with the measurement of iCa and if this interference can account for the typically observed in vivo effects of ethanol consumption on blood iCa levels.

METHODS

Ethanol (0-5 microl/ml) was added to blood or iCa standards and the iCa concentration measured using the ICA2 iCa analyzer (Radiometer) or the I-Stat Clinical Analyzer (Abbott Laboratories). Both instruments use an ion selective electrode to measure iCa. The relationship between iCa and BAC determined from the ex vivo addition of ethanol to blood was compared with relationships obtained in vivo during chronic ethanol consumption.

RESULTS

Addition of ethanol to blood or iCa standards resulted in a dose-dependent decrease in iCa concentration when iCa was measured using the ICA2 analyzer but had no effect on iCa concentration when measured with the I-Stat Clinical Analyzer. Ethanol's effect on iCa with the ICA2 analyzer did not differ between blood and standards, and ethanol had no effect on pH, suggesting that the ethanol-induced decrease in iCa was due to a methodological artifact. However, the magnitude of ethanol's effect was small and does not account entirely for the relationship between iCa and BAC observed in vivo with chronic ethanol consumption.

CONCLUSION

Ethanol can interfere with the measurement of iCa using ion selective electrodes, but this interference depends on the analyzer used. This is a significant methodological issue that has largely been unrecognized in the field of alcohol research. Although this interference does not explain entirely the relationship between iCa and BAC observed in vivo in studies on chronic ethanol consumption, it complicates investigations designed to assess the effect of ethanol on Ca homeostasis.

Effect of Duration of Maternal Alcohol Consumption on Calcium Metabolism and Bone in the Fetal Rat

BACKGROUND

Prenatal ethanol exposure can retard fetal growth and delay skeletal development. Ethanol also impairs maternal calcium (Ca) homeostasis and this impairment could mediate some of ethanol's effects on the fetal skeleton. Our previous studies suggest that the duration of maternal ethanol consumption may be an important factor for determining the severity of ethanol's effects on Ca homeostasis and fetal skeletal development. The purpose of this study was, therefore, to determine the effect of the duration of maternal ethanol consumption on fetal growth and skeletal development and to investigate the possibility that ethanol's effects may be related to perturbations in fetal/maternal Ca homeostasis.

METHODS

Rats were fed ethanol (36% ethanol-derived calories) in liquid diets for 3 weeks (days 1-21 of gestation) or 6 weeks (for 3 weeks before and throughout gestation). Fetuses were collected on day 21 of gestation, and body weight and length were measured. Fetuses were stained to determine the degree of skeletal ossification, and fetal blood was analyzed for ethanol, Ca (total and ionic Ca), albumin, parathyroid hormone (PTH), and osteocalcin.

RESULTS

Maternal ethanol consumption decreased fetal growth and delayed fetal skeletal development. Although there was a trend for fetal body length and serum osteocalcin levels to be more severely affected with an increased duration of maternal ethanol consumption, duration had no effect on fetal body weight or skeletal ossification. Fetal Ca homeostasis was also affected by ethanol exposure, with fetal hypocalcemia apparent after 6 weeks of maternal ethanol intake. A significant inverse relationship was found between fetal blood Ca levels and blood alcohol concentration (BAC), suggesting that the severity of the fetal hypocalcemia may have been related to differences in fetal BAC, rather than duration of maternal ethanol intake. Fetal serum PTH levels did not differ significantly among treatment groups indicating that the fetal hypocalcemia was not caused by a decrease in PTH levels.

CONCLUSIONS

Prenatal ethanol exposure impaired Ca homeostasis and skeletal development in the fetal rat. The severity of ethanol's effects was only marginally dependent on the duration of maternal ethanol consumption per se and seemed to be more related to the relative exposure of the fetus to ethanol (fetal BAC). The relationship between the ethanol-induced fetal hypocalcemia and skeletal effects remains to be determined.

Effect of Duration of Alcohol Consumption on Calcium and Bone Metabolism During Pregnancy in the Rat

BACKGROUND

Little is known about the consequences of drinking during pregnancy for the long-term health of the mother. Alcohol (ethanol) has been shown to disrupt calcium (Ca) homeostasis and is known to have deleterious effects on bone. During pregnancy, bone turnover is increased to maintain Ca homeostasis; therefore, pregnancy may be a time of life when maternal bone is particularly susceptible to the effects of ethanol. This study investigated the effect of duration of ethanol consumption on Ca homeostasis and bone during pregnancy in the rat.

METHODS

Rats were fed ethanol (36% ethanol-derived calories) in liquid diets for 3 (21 days gestation only) or 6 (3 weeks before and throughout 21 days gestation) weeks. Maternal blood was analyzed for Ca (total and ionized Ca [iCa]), the Ca-regulating hormones (parathyroid hormone [PTH], 1,25(OH)2D, calcitonin), and osteocalcin (a marker for bone formation). Bone was analyzed for ash (mineral) content.

RESULTS

Dams consuming ethanol (E dams) had decreased blood Ca levels (total and iCa) at both 3 and 6 weeks, but iCa was lower in E dams after 6 compared with 3 weeks. Importantly, ethanol seemed to interfere with the normal compensatory response to these decreased Ca levels. In contrast to pair-fed controls, serum PTH levels actually were decreased, 1,25(OH)2D levels failed to increase, and calcitonin levels were increased in ethanol-consuming dams, regardless of duration. Moreover, ethanol decreased bone formation, as indicated by serum osteocalcin levels, after both 3 and 6 weeks consumption, and after 6 weeks, the ash content of bone also was decreased. In addition, a relationship was found between the blood alcohol concentration (BAC) and some measures of Ca and bone metabolism. Serum 1,25(OH)2D and osteocalcin levels varied inversely, whereas serum calcitonin varied directly with BAC, suggesting that time of sampling after drinking may be an important variable for interpreting ethanol's effects on Ca and bone metabolism. In all rats, serum osteocalcin levels varied directly with PTH and 1,25(OH)2D levels.

CONCLUSIONS

Ethanol consumption during pregnancy impaired Ca homeostasis in the dam, regardless of duration of consumption, and resulted in decreased bone formation and ash content of bone. Significant relationships among the Ca-regulating hormones, BAC, and osteocalcin support the hypothesis that ethanol's effects on the Ca-regulating hormones may mediate some of its effects on bone.

Skeletal response to alcohol

This review briefly assesses the well-established effects of alcohol consumption on bone and mineral metabolism and addresses areas of controversy that need additional research. Alcohol consumption is a risk factor for osteoporosis based on the frequent finding of a low bone mass, decreased bone formation rate, and increased fracture incidence in alcoholics. Alcohol also has been shown to reduce bone formation in healthy humans and animals and to decrease proliferation of cultured osteoblastic cells. On the other hand, it has been difficult to demonstrate alcohol-induced bone loss and increased fracture rate in population-based studies. Indeed, most population-based studies have shown a positive association between alcohol and bone mass and no change or a decrease in fracture risk. Overall, the evidence generally supports a detrimental effect of chronic alcohol abuse on the skeleton of men and a neutral or generally beneficial effect of light to moderate alcohol consumption, especially in older women. This latter putative beneficial effect may be due to a reduction in the age-related increase in bone remodeling associated with postmenopausal bone loss. Specific areas of research are recommended to clarify the dose and sex effects of alcohol consumption and to determine cellular and molecular mechanisms of action. The goals of this proposed research emphasis are to determine the degree of risk for the range of alcohol consumption, to set guidelines of consumption compatible with maintaining bone health, and to develop appropriate countermeasures to prevent or reverse the detrimental skeletal effects of alcohol abuse.

Moderate alcohol consumption suppresses bone turnover in adult female rats

Chronic alcohol abuse is a major risk factor for osteoporosis but the effects of moderate drinking on bone metabolism are largely uninvestigated. Here, we studied the long-term dose-response (0, 3, 6, 13, and 35% caloric intake) effects of alcohol on cancellous bone in the proximal tibia of 8-month-old female rats. After 4 months of treatment, all alcohol-consuming groups of rats had decreased bone turnover. The inhibitory effects of alcohol on bone formation were dose dependent. A reduction in osteoclast number occurred at the lowest level of consumption but there were no further reductions with higher levels of consumption. An imbalance between bone formation and bone resorption at higher levels of consumption of alcohol resulted in trabecular thinning. Our observations in rats raise the concern that moderate consumption of alcoholic beverages in humans may reduce bone turnover and potentially have detrimental effects on the skeleton.

Acute effect of EtOH on Mg2+ homeostasis in liver cells: evidence for the activation of an Na+/Mg2+ exchanger

The acute administration of ethanol mobilizes a considerable amount of Mg2+ from perfused rat livers and isolated hepatocytes in a dose-dependent fashion in the absence of release of cellular K+ or lactate dehydrogenase (LDH) in the extracellular medium. Mg2+ extrusion becomes detectable within 2 min and reaches the maximum within 8 min after ethanol addition, declining toward the basal value thereafter irrespective of the persistence of alcohol in the perfusion system and the dose of ethanol administered. The effect is the result of a specific impairment of Mg2+ transport and/or regulatory mechanisms. In fact, Mg2+ extrusion does not occur under conditions in which 1) ethanol is replaced by an equivalent dose of DMSO, 2) amiloride or imipramine are used as inhibitors of the Na+/Mg2+ exchanger, 3) extracellular Na+ is replaced by an equimolar concentration of choline chloride, and 4) 4-methylpyrazole is used to specifically inhibit alcohol dehydrogenase and cytochrome P-4502E1. Finally, the observation that the cellular level of ATP is markedly reduced after acute ethanol administration would suggest that Mg2+ extrusion results from a decreased buffering capacity of cytosolic Mg-ATP complex.

Effects of ethanol on gene expression in rat bone: transient dose-dependent changes in mRNA levels for matrix proteins, skeletal growth factors, and cytokines are followed by reductions in bone formation

Several studies were performed in female rats to determine dose and time course changes in mRNA levels for matrix proteins in bone after a single administration of ethanol. As expected, dose-dependent transient increases in blood ethanol were measured. Additionally, there was mild hypocalcemia with no change in immunoreactive parathyroid hormone. Coordinated dose-dependent increases in mRNA for type 1 collagen, osteonectin, and osteocalcin were noted in the proximal tibial metaphysis 6 hr after ethanol was given, with the peak values occurring at a dose of 1.2 g/kg (0.4 ml). Similar increases in mRNA levels for matrix proteins were noted in lumbar vertebrae after ethanol treatment. The changes were specific for bone; ethanol had no effect on mRNA levels for matrix proteins in the uterus or liver, although the mRNA concentrations tended to be reduced in uterus. Message levels for several cytokines implicated in the regulation of bone turnover were also assayed; mRNA levels for transforming growth factor-beta1, transforming growth factor-beta2, interferon-gamma, and interleukin-6 were unchanged at doses ranging from 0.14 to 1.7 g/kg. At the highest dose of ethanol, the mRNA level for tumor necrosis factor-alpha was elevated while the level for insulin-like growth factor-1 was reduced. The time course effects of ethanol (0.4 ml dose) were determined in a separate experiment. Ethanol resulted in a transient increase in mRNA levels for the three bone matrix proteins assayed. However, matrix protein synthesis, as determined by incorporation of 3H-proline into the proximal tibial metaphysis, was not changed after 6 hr. The changes in mRNA levels for the matrix proteins were preceded by brief, transient decreases in mRNA levels for interleukin-1beta, interferon-gamma, and migration inhibitory factor, and followed by a more prolonged decrease in the mRNA level for insulin-like growth factor-1. A subsequent study was performed to determine the effects of repetitive daily treatment with ethanol on rat bone. After 7 days, there were highly significant decreases in the mRNA level for type 1 collagen, as well as decreased bone formation. These results suggest that ethanol may alter bone metabolism by disturbing signal transduction pathways that regulate the expression of genes for bone matrix proteins, skeletal growth factors, and cytokines.

Alcohol, osteoporosis, and bone regulating hormones

The mechanism of the production of ethanol-associated osteopenia seems to be a direct effect of alcohol on bone cells and an indirect or modulating effect through mineral regulating hormones such as vitamin D metabolites, parathyroid hormone, and calcitonin. The modulating effects of these hormones on bone and mineral metabolism in acute and chronic alcohol consumption is discussed herein.

Alcohol consumption inhibits bone growth and development in young actively growing rats

Adolescence is an age of widespread alcohol abuse, but the effect of alcohol consumption on bone formation has not been studied in the young population. This study addresses the effect of alcohol on the early phases of bone growth and development in an animal model. Four-week-old, female Sprague-Dawley rats were divided into three groups. Alcohol-treated animals were fed a modified Lieber-DeCarli diet ad libitum containing 35% ethanol-derived calories, whereas the pair-fed animals (weight-matched to ethanol rats) received an isocaloric liquid diet in which maltose-dextrin substituted calories supplied by ethanol. Chow animals were fed a standard rat chow ad libitum. Proximal tibiae (primarily cancellous bone) and femora (primarily cortical bone) were removed for analysis after 2, 4, 6, or 8 weeks on the diets. Serum was collected for analysis of calcium levels, osteocalcin, corticosterone, growth hormone, parathyroid hormone, and 25-hydroxyvitamin D. The most rapid weight gain occurred between 6 and 8 weeks of age, it was significantly delayed in alcohol and pair-fed animals. Almost all morphological parameters of bone were lower in the alcohol groups. No significant difference in serum calcium levels, osteocalcin, or growth hormone levels were found, and small difference in calciotropic hormone levels was found between groups. The results indicated that chronic alcohol consumption during the age of bone development reduces bone density and peak bone mass in both cortical and cancellous bone. The mechanism whereby this effect occurs is not fully understood, but, our results suggest that the negative impact of alcohol on growing bone is not due to the secondary effects of altered bone mineral regulating hormones.

Combined effects of caffeine and alcohol during pregnancy on bones in newborn rats

The combined effects of caffeine and alcohol on mineral contents of fetal mandibles and femurs were studied. Pregnant rats were divided into four groups: group 1, control; group 2, caffeine; group 3, alcohol; and group 4, caffeine-plus-alcohol. Alcohol (1.0 g ethanol/kg body weight) was intubated twice daily, beginning at day 9 of gestation. Caffeine (2 mg/100 g body weight) was given as a dietary supplement. Groups 1 and 2 were intubated with isocaloric sucrose solution. At birth, randomly selected pups were killed and the mandible and femur were removed and dried. Ca, P, Mg, Zn and hydroxyproline in these bones were measured. Notwithstanding the dams' intake of caffeine and alcohol administered separately, the present results suggest that the combination of caffeine and alcohol exhibited the most detrimental effects.

Acute effects of alcohol ingestion on the human serum concentrations of calcium and magnesium

Alcohol has been shown to reduce serum calcium concentrations in several animal studies. In humans, using relatively low doses of alcohol, however, the results were inconclusive. In addition, the effect of alcohol consumption on serum magnesium concentrations is controversial. To elucidate the influence of alcohol ingestion on serum calcium and magnesium in humans 43 intoxicated patients and seven healthy volunteers who had not previously ingested alcohol were studied. There was an inversely related diminuition of serum calcium and magnesium concentrations with increasing serum alcohol. These effects of alcohol may play a role in the metabolic and clinical disorders observed in severely intoxicated people.

Interactive effects of ethanol intake and maternal nutritional status on skeletal development of fetal rats

Skeletal development on gestation day 21 was examined in fetuses of alcohol-consuming (A), pair-fed (PF) and ad lib-fed (C) Sprague-Dawley females. Ethanol (36% ethanol-derived calories) was administered in liquid diets that were marginal (Diet A1) or optimal (Diet A2) in terms of pregnancy requirements (18% vs. 25% total calories as protein, respectively). For each bone studied, a lengthwise measurement was made of the whole bone and of the ossified portion(s), and percent ossification was calculated. Number of sternebral ossification centers present was also determined. Alcohol-exposed fetuses showed retarded ossification of the tibia and radius, regardless of maternal protein intake. Increasing the protein content of the alcohol diet from 18% (Diet A1) to 25% (Diet A2) significantly increased ossification of the ulna, sternum, humerus and ilium-ischium. For the ulna, A2 fetuses showed greater ossification than A1 fetuses but were still retarded compared to PF and C fetuses. For the sternum, humerus and ilium-ischium, however, ossification in A2 fetuses increased to the levels observed in the PF and C groups. In addition, number of sternebral ossification centers present was significantly increased in A2 compared to A1 fetuses. These data indicate that skeletal development provides a sensitive index of ethanol-induced developmental delay as well as interactive effects of ethanol and nutrition.

The response of circulating parameters of bone mineral metabolism to ethanol- and EDTA-induced hypocalcemia in the rat

The mechanism of the acute hypocalcemia that follows acute ethanol administration has not been established. Measurements of parathyroid hormone (PTH) performed during this hypocalcemia reveal conflicting results. We compared the response of ionized calcium (Ca2+), immunoreactive PTH and bone Gla protein (BGP) after ethanol- and EDTA-induced hypocalcemia. 103 male Sprague Dawley rats each weighing approximately 300 g received ethanol and 100 rats of similar weight received EDTA. In each of these studies the animals were divided into experimental and control groups. The ethanol-treated rats received ethanol, 2 g/kg body weight, by ip injection and the EDTA-treated rats received 100 mg EDTA/kg body weight by im injection. Controls received normal saline by the corresponding route of administration. Rats were sacrificed at 0, 30, 60, 90, 180 and 360 min for the measurement of the above parameters. In both experimental groups Ca2+ levels were significantly reduced to the same degree by 30 min with return to control values by 360 min. There was no significant difference in immunoreactive PTH, and BGP between control and ethanol-treated groups. In the EDTA-treated rats, however, PTH values were significantly increased at 30 (P less than 0.005) and BGP at 60 and 90 minutes (P less than 0.005) vs. control. Therefore acute ethanol administration appears to blunt the PTH response to hypocalcemia. A direct inhibitory effect of ethanol on osteoblast function ie BGP production cannot be excluded. In addition, PTH may stimulate BGP.

Acute hypocalcemic effect of ethanol in dogs

Ethanol has been shown to reduce serum calcium in multiple animal studies. However, in human studies done using lower doses of alcohol, only inconclusive results have been obtained. This study was undertaken to evaluate the effects of varying doses of oral ethanol on total serum calcium. Fifteen adult mongrel dogs (17-25 kg) were divided into three groups which differed in the dosage of ethanol given. Group I animals received 0.5 g/kg of ethanol; Group II, 1.0 g/kg ethanol; and Group III, 2.0 g/kg of ethanol. Venous blood was sampled for estimation of concentrations of total serum calcium and ethanol. In the animals in Group I, serum calcium levels were unchanged by the ethanol. In both Groups II and III, significant reductions in serum calcium were demonstrated, which occurred within 5 min of intoxication. The mean decrease in serum calcium in Group III animals was significantly greater than that in either Group I and II. We conclude that the rapid hypocalcemic effect requires a threshold amount of ethanol before it becomes chemically evident. This critical value in dogs approximated 1 g/kg which results in a mean peak serum alcohol concentration of 117 +/- 6 mg/dl.

Bone changes in alcoholic liver cirrhosis. A histomorphometrical analysis of 52 cases

Bone biopsies of 52 histologically confirmed alcoholic cirrhotic patients and 15 age- and sex-matched controls have been histomorphometrically analyzed determining trabecular bone volume (TBV), mineralized bone volume (MBV), and osteoid volume (OV). We also determined serum PTH, 25-OH-D3, calcitonin, FSH, LH, estradiol, testosterone, T3 and T4, urine cortisol, routine liver function tests, serum and urinary calcium, phosphorus, and magnesium. We found a high prevalence of osteoporosis: TBV was significantly lower in cirrhotic patients (T = 7.23, P less than 0.001), 41 of them being in the range of osteoporosis; none of them had osteomalacia. Levels of all the above-mentioned hormones and electrolytes were almost normal, and no correlation was found between them and liver function tests, as occurred with the bone parameters.

Chronic alcohol treatment results in disturbed vitamin D metabolism and skeletal abnormalities in rats

The effect of chronic alcohol consumption on the skeleton was investigated in rats. The treated group received ethanol administered as 38% of caloric intake in a liquid diet (Sustacal) for 10 months. The control rats were pair weighted to the ethanol-treated animals throughout the study; the growth curves of the two groups were the same. The controls were given the same liquid diet except that dextrin:maltose (3:1) was substituted isocalorically for ethanol. Ethanol-treated rats did not differ from the pair-weighted controls in mean serum calcium, phosphorous, or creatinine. In contrast, serum magnesium was reduced (p less than 0.02) in alcohol-treated rats. Ethanol treatment also resulted in changes in the serum concentrations of vitamin D metabolites; serum 25-hydroxyvitamin D3 was increased (p less than 0.001), while serum 1,25-dihydroxyvitamin D3 was decreased (p less than 0.01). Tibial length was reduced in ethanol-treated rats (p less than 0.05) but there was no change in femoral length. Medullary area was increased in tibial diaphyses from alcohol-treated rats compared to weight matched control animals (p less than 0.01), indicating a net increase in resorption. The cross-sectional area of the tibial diaphysis of ethanol-treated rats was the same as the matched controls. Trabecular bone was decreased in the tibial metaphysis of ethanol-treated rats compared to the matched controls (p less than 0.05) indicating a net loss of trabecular bone. Ethanol treatment did not have an effect on the organic weight of the femur but the ash weight was reduced (p less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of ethanol on serum electrolytes and osmolality

Rats and rabbits were injected ethanol 2 g/kg intraperitoneally. One hour after injection blood was analyzed for serum electrolytes and osmolality. Administration of ethanol caused decrease in serum sodium (p less than 0.0005), potassium (p less than 0.0005), calcium (p less than 0.0005), chloride (p less than 0.005), magnesium (p less than 0.0005) in rabbits. Further studies of intraperitoneal administration of ethanol in rats showed decrease in concentration of sodium (p less than 0.025), potassium (p less than 0.025), calcium (p less than 0.01) chloride (p less than 0.005) magnesium (p less than 0.005), phosphorus (p less than 0.025) and glucose (p less than 0.005). Administration of ethanol caused an increase in serum osmolality in both rabbits and rats (p less than 0.005, p less than 0.05). It is concluded that ethanol ingestion is probably the commonest cause of the hyperosmolar state. Although the osmotic and sedative effects of ethanol are pharmacologically unrelated, the presence of ethanol should be considered in comatose patients in whom the measured plasma osmolality appreciably exceeds that predicted on the basis of plasma glucose, urea and electrolytes concentration.

Osteopenia

Osteopenia in the elderly is responsible for 1.3 million fractures per year in the United States. The acute care costs associated with this disorder are between $6 and $10 billion dollars annually. Although much has been learned over the last few years of the factors that predispose patients to osteoporosis and how these factors may be avoided, the precise pathophysiologic mechanisms for bone loss remain obscure. Significant technological advances have been made in the 1980s in the development of noninvasive methods for measuring bone mineral density that give indirect assessments of bone mass. However, these methods are very controversial, are not suitable for mass screening for detecting subjects potentially at risk, and have a limited place in routine clinical care. Osteoporosis is characterized by thinning and fragmentation of trabecular bone, which is probably irreversible when it is far advanced. The most reasonable therapeutic approach may be prevention, which can be achieved in many patients by estrogen therapy in the perimenopausal years and insuring an adequate dietary calcium intake, particularly in adolescents and in the elderly. Physical activity throughout life is also likely to be important in maintaining adequate bone mass. It is important to differentiate osteoporosis from other causes of osteopenia, for example, osteomalacia, primary hyperparathyroidism, and malignant diseases such as myeloma, since these bone diseases have a different natural history, pathophysiology, and treatment.

Tolerance to ethanol in the rat vas deferens. Effect of a calcium channel antagonist

Previous research from this laboratory indicated that ethanol dose-dependently depressed vas deferens contractions. The experiments described here examine the role calcium plays in the inhibitory action of ethanol in this tissue. Rat vas deferens tissues obtained from control (dextrin maltose) or chronically ethanol-treated animals were stimulated in the absence and then in the presence of 181 mM ethanol and/or a calcium channel blocker. Increasing the extracellular calcium concentration from 2.1 to 5.0 mM decreased ethanol's in vitro inhibitory effect on contractions induced by norepinephrine, KCl or electrical stimulation. Following chronic in vivo ethanol administration, increasing the calcium concentration to 5 mM blocked this inhibition. Nifedipine, a calcium channel antagonist inhibited vas deferens contractions. In the presence of nifedipine, in vitro ethanol further depressed vas deferens contractions stimulated by norepinephrine, K+ and by electrical stimulation. In vivo ethanol treatment attenuated ethanol's inhibition in vitro, and reduced the blocking effect of the calcium antagonist on mechanical responses of the vas in ethanol-free medium. These data suggest that changes in calcium mobilization are involved in both the acute action of ethanol and the development of tolerance.

Deranged bone mineral metabolism in chronic alcoholism

Chronic alcoholic subjects may suffer from osteopenia with either osteomalacia or osteoporosis as the main histologic finding. The reasons may be multifactorial, including nutrition, direct effects of alcohol on bone, and deranged liver function. Seventeen asymptomatic subjects with chronic alcoholism were studied. Serum PTH (carboxyl and midmolecule fragments), 25 hydroxyvitamin D [25(OH)D], 1-25 dihydroxyvitamin D [1-25(OH)2D], and ionized calcium were measured in each subject. In addition to these tests, we employed a sensitive technique of dual photon absorptiometry to measure vertebral bone density and a radioimmunoassay of serum bone gla protein (BGP) to estimate osteoblast function. Our results show that subjects suffering from chronic alcoholism had significantly lower serum 25(OH)D and higher ionized calcium, BGP, PTH (midmolecule) and 1,25(OH)2D while four patients had bone density values below the fracture threshold (0.96 g/cm2). These findings demonstrate that asymptomatic patients with chronic alcoholism have deranged bone mineral metabolism including abnormal BGP and some subjects may even have abnormal dual photon absorptiometry measurements. These particular subjects may be at risk in the future for developing osteopenia and consequent vertebral compression fractures.

Demonstration that ethanol inhibits bone matrix synthesis and mineralization in the rat

The effects of ethanol on bone and mineral metabolism were investigated in 3 groups of male rats. The first group received ethanol administered as 36% of caloric content in a liquid diet for 3 weeks. A second group of pair-fed animals was given the same liquid diet, except that sucrose was substituted isocalorically for ethanol. A third group of rats was fed standard laboratory chow. The ethanol-treated rats gained significantly less weight than laboratory chow-fed controls but gained the same weight as the pair-fed animals. Ethanol-treated rats had a modest but significant decrease in mean serum calcium compared to pair-fed controls (10.3 +/- 0.1 vs. 10.6 +/- 0.1 mg/dl, p less than .001). Mean serum phosphate, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D and immunoreactive parathyroid hormone were the same in the 3 groups. The ethanol-treated animals showed significant decreases in mean tibial length (1.88 +/- 0.01 vs. 1.98 +/- 0.02 cm, p less than .01), mean endosteal bone formation rate (0.0006 +/- 0.0001 vs. 0.0026 +/- 0.0003 mm3/day, p less than .001) and mean periosteal bone formation rate (0.022 +/- 0.001 vs. 0.026 +/- 0.001 mm3/day, p less than .01) compared to the pair-fed controls. The ethanol-treated rats demonstrated significant decreases in mean periosteal mineralization rate (7.5 +/- 0.3 vs. 10.3 +/- 0.6 micron/day, p less than .01) and mean periosteal apposition rate (8.5 +/- 0.5 vs. 11.0 +/- 0.8 micron/day, p less than .05) and a significant increase in mean periosteal osteoid thickness (15.5 +/- 1.4 vs. 10.4 +/- 0.8 micron, p less than .01) compared to pair-fed controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Disorders of divalent ions and vitamin D metabolism in chronic alcoholism

This chapter reviews the pathogenesis of disordered divalent mineral and bone metabolism in alcoholism, emphasizing the role of impaired vitamin D physiology. Normally, vitamin D metabolites are derived principally from cholecalciferol, which is synthesized in the skin via the energy of sunlight. Most alcoholics have subnormal levels of 25-hydroxyvitamin D [25(OH)D]. Those with Laennec's cirrhosis also have low levels of vitamin D binding protein due to impaired hepatic protein synthesis and as a result, have low serum concentrations of total, but not free, 1,25-dihydroxyvitamin D. The causes of 25(OH)D deficiency in alcoholics include reduced hepatic 25-hydroxylase activity, lack of sun exposure, inadequate dietary intake, and malabsorption. Hypomagnesemia and hypophosphatemia, which are very common in hospitalized alcoholics, result from deficient intake, malabsorption, excessive renal losses, and cellular uptake of both ions. Hypocalcemia in alcoholics is caused primarily by hypoalbuminemia but can result also from deficient intake, malabsorption, hypomagnesemia, and renal calcium wastage. Low vitamin D activity may contribute significantly to the calcium and phosphate deficiencies. Osteoporosis is extremely common in alcoholics whereas osteomalacia is exceptional. However, both bone disorders respond well to vitamin D therapy. Thus, alcoholics should be screened periodically for vitamin D deficiency and osteopenia, and when either is detected they should receive vitamin D supplements.

Inhibition of net calcium efflux from bone by ethanol in vitro

Ethanol administered to animals is known to cause hypocalcemia. This investigation was undertaken to evaluate direct early effects of ethanol on the net fluxes of Ca2+ and inorganic phosphate (Pi) into or out of bone using tibiae from 13-day-old chick embryos and 8-day-old suckling rats in vitro. When chick bones were incubated with ethanol in the medium (10 microliters/ml), net Ca2+ efflux was decreased 19, 22, 27, and 31% at 2, 4, 6, and 8 h, respectively. Metabolically inhibited bones showed a net influx rather than efflux of Ca2+ and were not further affected by ethanol. The ethanol had no consistent effect on net Pi efflux and slightly reduced lactate production. At three doses of ethanol (3, 10, and 30 microliters/ml of medium) the reduction of Ca2+ efflux was dose related in both chick and rat bones. Ethanol completely inhibited parathyroid hormone-stimulated, net Ca2+ efflux from chick bones, even at ethanol levels that by themselves did not affect Ca2+ efflux. These findings are consistent with the hypothesis that the hypocalcemia in ethanol-treated animals may be due in part to inhibition of net Ca2+ efflux from bone.

The effects of alcohol on blood pressure and electrolytes

The interaction between alcohol abuse, changes in blood pressure, and electrolyte abnormalities is complex. Some effects of alcohol are seen only with acute ingestion, some during withdrawal, and some only in chronic drinkers. Careful attention to the interactions between the metabolism of various electrolytes can prevent unnecessary morbidity and mortality in alcoholic patients.

Evidence of a toxic effect of ethanol on bone in rats

Tibiae from rats treated chronically for 12 days with enough ethanol to induce physical dependence were found to have an increased incidence of fracture during dissection and cleaning (7 of 12 or 58%) compared to control animals (1 of 12 or 8%). The site of the fractures, the proximal end of the tibia, showed an increased opacity to X-rays, and the dried bones were distinctly darker in appearance than similarly prepared control bones. The effects noted in our study suggest that the rat model could be useful for the study of the mechanisms by which alcohol affects bone growth, remodeling, and strength. These studies might shed new light on the pathogenesis of increased bone fragility in alcoholics.

Acute effects of ethanol and acetaldehyde on plasma phosphate level

Oral administration of ethanol in a dose of 65 mmol kg-1 produced marked change of plasma phosphate level in rabbits. Hypophosphataemia was observed for the first 2 h after administration followed by significant increase of plasma phosphate at 5 h. Hypophosphataemia did not appear when ethanol was given to the rabbits pretreated with pyrazole. When animals were injected with disulfiram in advance, the duration of hyperphosphataemia due to ethanol was prolonged. Administration of acetaldehyde at a dose of 1.5 mmol kg-1 produced hyperphosphataemia. In this study, plasma phosphate was not associated with change in calcium level. These results suggest that the hypophosphataemia observed was related to the metabolic process of ethanol utilizing alcohol dehydrogenase, and that acetaldehyde, a metabolite of ethanol, might induce the hyperphosphataemia in the animals.

Interrelationships between vitamin D3 and 25-hydroxyvitamin D3 during chronic ethanol administration in the rat

Vitamin D [D] depleted female Sprague-Dawley rats were fed for a period of 4 wk a D deficient diet containing 36% of total calories as ethanol while control animals received an isocaloric regimen where ethanol was substituted for by dextrins. In conjunction with the ethanol feeding 92 I.U. of [14C]-vitamin D3 [(14C)-D3] were administered by intragastric gavage 3 times 1 wk for 3 2/3 wk. At the end of the experiment, [14C]-D3 and [14C]-25-hydroxyvitamin D3 [(14C)-25(OH)D3] concentrations were analyzed in plasma, liver, striated muscle and adipose tissue. Body reserves in unchanged [14C]-D3 were significantly reduced by ethanol treatment as seen by 24%, 26%, and 59% lower plasma (p less than 0.02), muscle (p less than 0.001) and adipose tissue (p less than 0.001) [14C]-D3 concentrations in ethanol-treated compared to control rats. In contrast total plasma and liver [14C]-25(OH)D3 content were increased by 30% (p less than 0.05) and 55% (p less than 0.001) respectively. This increased liver and plasma [14C]-25(OH)D3 following ethanol treatment was not accompanied by a proportional [14C]-25(OH)D3 incorporation into muscle and adipose tissue. These results suggest that during steady state conditions 25(OH)D3 production is increased during chronic ethanol administration while the body pool in unchanged D3 is significantly lowered. These results also point out that in the rat plasma 25(OH)D concentrations are not a reliable guide for the determination of vitamin D status during chronic ethanol administration.

Parathyroid hormone effects on calcium metabolism in the rat are impaired by 5-ethyl-5'-(1-methylpropyl)-2-thiobarbiturate (inaktin)

The mechanism by which inaktin, a thiobarbiturate, promotes a moderate drop in serum calcium has been investigated. The effect was cancelled in hypocalcemic parathyroidectomized rats. On the other hand inaktin antagonized the serum calcium raising effects of parathyroid extract in these animals. In rats wit intact parathyroid glands inaktin caused a two-fold increase in urinary calcium excretion and a marked decrease in body and bone calcium turnover (measured with 45 Ca). These results support the view that inaktin impairs the parathyroid hormone effects on calcium metabolism.

Effect of alcohol ingestion on bone and mineral metabolism in rats

Chronic ethanol administration to growing rats for 56 days resulted in circulating levels of 140 mg/dl, approximating concentrations that characterize alcoholic intoxication in man. This degree of alcohol ingestion, although without gross or histological effect on the liver or testicles, was attended by decreased trabecular bone volume despite a normal rate of skeletal mineralization as measured by time-spaced tetracycline labeling. Concomitant serum levels of calcium, phosphate, magnesium, creatinine, glutamic oxalacetic transaminase, alkaline phosphatase, testosterone, and 25-hydroxyvitamin D were normal. Although alcohol treatment was associated with a significant decrease in urinary calcium excretion, it had no effect on phosphate excretion nor on its renal tubular reabsorption. The data reveal that circulating levels of alcohol that do not result in hepatic or testicular injury are toxic for bone.

Effect of acute ethanol loading on parathyroid gland secretion in the rat

Acute ethanol loading in the rat induces hypocalcemia and hypermagnesemia. In addition, hypocalcemia is not corrected by exogenous PTH. In the rat the mechanism of these changes was investigated by measuring plasma immunoreactive parathyroid hormone (PTH). PTH was also measured in culture medium in which parathyroid glands were incubated. The addition of ethanol to test tubes did not interfere with PTH measurement. Absolute ethyl alcohol diluted to 50% with distilled water was administered via an intragastric tube. It failed to induce an increase in plasma immunoreactive PTH level. Similarly, it prevented an increase in plasma PTH after disodium EDTA injection. Thus in the presence of ethyl alcohol plasma PTH failed to increase in spite of a significant decrease of plasma calcium. In vitro studies showed that the decrease of calcium concentration of the medium from 1.50 to 0.75 mmol/l was associated with a 3 to 5 times increase in PTH secretion rate. This increase was suppressed when ethanol was added to the culture medium. In conclusion, ethanol loading via gastric tubing induced: 1) decrease in plasma calcium; 2) suppression of immunoreactive PTH secretion in the presence of hypocalcemia. It is postulated that the acute hypocalcemic effect of ethanol loading is mediated by a dual effect at the level of the bone and the parathyroid gland.

Effects of acute ethanol intoxication, chronic ethanol intoxication, and ethanol withdrawal on magnesium and calcium metabolism in the rat

Effects of ethanol intoxication and withdrawal on magnesium and calcium metabolism were studied in rats. During acute ethanol intoxication, plasma [Mg2+] was increased and plasma [Ca2+] decreased. During chronic intoxication, plasma [Mg2+] was normalized whereas plasma [Ca2+] was persistently subnormal. Ethanol withdrawal was followed by a decrease in plasma [Mg2+] and a normalization of plasma [Ca2+]. These various changes are probably related to changes in systemic pH and to the biochemical effects of ethanol and ethanol withdrawal on intermediary metabolism. Cerebrospinal fluid [Mg2+] was unchanged during intoxication and withdrawal and it was concluded that no etiological role can presently be ascribed to the magnesium ion as far as cerebral signs of ethanol intoxication and withdrawal in the rat are concerned. No consistent changes in erythrocyte [Mg2+] were encountered during ethanol intoxication and withdrawal in rats.

Adenosine 3',5' cyclic monophosphate, calcium and magnesium excretion in ethanol intoxication and hangover

Effect of ethanol on adenosine 3', 5' cyclic monophosphate (cAMP), calcium (Ca) and magnesium (Mg) excretion was studied in controlled clinical conditions in man. Seven male volunteers served as their own controls. In 5 subjects cAMP excretion was primarily suppressed by ethanol. Ethanol appeared to have a biphasic effect on Ca excretion, an initial stimulation followed by a conservation phase. Mg excretion was stimulated by ethanol in 5 subjects. Subjects having nausea and vomitus and the most severe hangover symptoms had the lowest urinary Ca excretion and the lowest imitial cAMP excretion. Ca and Mg metabolism and the susceptibility of the body to the toxic effects of ethanol appeared to be interrelated.

Alcohol tolerance in a cholinergic nerve terminal: relation to the membrane expansion-fluidization theory of ethanol action

Phrenic nerve terminals from rats subjected to long-term ethanol treatment were more resistant to ethanol (in vitro) than terminals from sucrose-fed rats, as measured by the effect of ethanol on the frequency of miniature end plate potentials. Long-term ethanol exposure may thus induce the synthesis of more rigid membrane lipids, reducing membrane "fluidizability". This may provide a neurocellular basis for ethanol tolerance and cross-tolerance with anesthetics and barbiturates.

Effects of ethanol on chicks in vivo and on chick embryo tibiae in organ culture

Hypocalcemia previously reported in rats and dogs following oral administration of ethanol may have been caused by a movement of calcium from blood to bone. This present study was undertaken to determine whether ethanol also causes hypocalcemia in chicks and to investigate the direct effects of ethanol on mineral accretion, glucose metabolism and growth of embryonic chick tibiae in an organ culture system. A high dose of ethanol (6 g/kg body wt) produced hypocalcemia, hypermagnesemia and an elevated hematocrit in chicks. Results in vitro were as follows: 1) 5 to 30 mul ethanol/ml medium produced dose-related increases in bone mineral from 58-440%; 2) lactate production was inhibited at all ethanol levels; 3) increased mineral accretion did not occur in ethanol-treated tibiae when iodoacetate was in the medium, but did occur in mechanically disrupted bones exposed to ethanol; and 4) the ethanol response in bone was directly related to the medium phosphate concentration. The results lead to the following conclusions: 1) ethanol has a direct stimulatory effect on bone mineral accretion and an inhibitory effect on bone glucose metabolism in vitro; 2) viable bone cells and an adequate phosphate supply are necessary for the ethanol response, but tissue integrity is not; and 3) the hypocalcemic effect of ethanol in vivo may at least partially result from ethanol-stimulated bone mineral deposition.

Some endocrine aspects of alcoholism

This review has focused on the more recent studies of ethanol-endocrine relationships. The data were evaluated from a fairly unbiased point of view and an attempt was made to point out some of the deficiencies in knowledge of the effects of ethanol on the endocrine system and the underlying mechanisms. The adrenal, for example, has been given the greatest attention in alcohol research, and yet the occurrence of atrophy or hypoplasia, despite alcohol's role as a stressor which can increase cortisol secretion, remains unexplained. In addition, our studies of the alcoholic subject have been conducted exclusively on the "skid-row" individual and may not be descriptive of the middle-class alcoholic subject who has not undergone similar nutritional and environmental stresses. While it is far from obvious that alcoholism is primarily an endocrine disease, the effects of ethanol on hormone metabolism are numerous and deserve further attention.