Low levels of ATP synthase and cytochrome c oxidase subunit peptide from hearts of copper-deficient rats are not altered by the administration of dimethyl sulfoxide

This study determined if reported decreases in the delta subunit of ATP synthase and nuclear-encoded cytochrome c oxidase subunits in hearts of copper-deficient rats were secondary to the heart disease pathology or due to lack of the trace element. Male weanling Long-Evans rats were randomly divided into six groups: rats fed a copper-adequate or copper-deficient diet (with free access) with or without 5% dimethyl sulfoxide (DMSO) in the drinking water and rats pair-fed the copper-adequate or copper-deficient diet without DMSO treatment. After 4 wk, rats in the groups fed the copper-deficient diet had lower liver superoxide dismutase and heart cytochrome c oxidase activities compared with groups fed the copper-adequate diet. Administration of DMSO, an antioxidant, and energy restriction (pair-feeding) partially blocked cardiac hypertrophy in rats fed the copper-deficient diet. Greater mitochondrial volume density and mitochondrial:myofibrillar ratio and disrupted myofibrils and basal laminae were observed in the hearts from rats fed the copper-deficient diet and not treated with DMSO compared with hearts from groups fed the copper-adequate diet. The DMSO-treated rats fed the copper-deficient diet had hearts with intact structure but enlarged mitochondria compared with other groups fed the copper-deficient diet. The delta subunit of ATP synthase and the nuclear-encoded cytochrome c oxidase subunits IV and V were depressed in rats fed a copper-deficient diet regardless of antioxidant treatment and pair-feeding. These data suggest that the effects of copper deficiency upon ATP synthase and cytochrome c oxidase proteins are not due to the cardiac pathology.

Submaximal, aerobic exercise training exacerbates the cardiomyopathy of postweanling Cu-depleted rats

To determine the dual effect of exercise training and copper depletion on myocardial function and ultrastructure, postweanling rats were either trained or sedentary while fed copper-adequate or copper-deficient diets for 8 wk. Rats developed characteristic myocardial subcellular degeneration and increased cardiac mitochondrial volume density when copper depleted, despite lack of overt cardiac hypertrophy, hypertension, or anemia. Training combined with copper depletion induced mild left ventricular hypertrophy. Basal laminae appeared fractionated in areas at capillary-myocyte interface, with focal pericapillary and interstitial collagen accumulation, whereas overt fibrosis was absent or minimal. Electrocardiograms revealed increased QRS wave and QT duration and notching of QRS complex with copper depletion, consistent with intraventricular conductance disturbances. The oxidative capacity of soleus muscle increased with training in copper-adequate rats, but was reduced with progressive copper depletion. These data suggest that copper depletion and training are synergistic in effecting focal accumulation of collagen, with deleterious effect on exercise capacity.

A unified perspective on copper deficiency and cardiomyopathy

Dietary copper restriction in rats results in cardiomyopathy. In rats fed copper-restricted diets from weaning for 5 to 8 weeks, a concentric hypertrophy is apparent, whereas postweaning copper restriction does produce cardiomyopathy without apparent hypertrophy. Both sets of circumstances appear to affect the integrity of the basal laminae of cardiac myocytes and capillaries. In rats fed copper-restricted diets from weaning, decreases in cytochrome c oxidase are related not only to copper's role as a coenzyme, but also to a marked decrease in the nuclear encoded subunits of the enzyme complex. Decreased levels of the delta-subunit of ATP synthase have been observed. However, such aberrations in mitochondrial enzymes, as well as morphologic alterations, apparently do not affect cardiac levels of ATP. This review suggests mechanisms of cardiac adaptation and initiation factors leading to cardiac hypertrophy. We present a hypothetical working model explaining the events leading to cardiac failure in the copper-deficient rat heart based on the present body of knowledge, and compare the pathology with other models of cardiomyopathies.

Diets containing corn oil, coconut oil and cholesterol alter ventricular hypertrophy, dilatation and function in hearts of rats fed copper-deficient diets

Cardiac hypertrophy and function were evaluated in rats fed diets containing deficient, marginal or adequate levels of copper. The fat concentration of the diets was either 10 g/100 g corn oil, 10 g/100 g coconut oil or 10 g/100 g coconut oil + 1 g/100 g added cholesterol. Left ventricular (LV) wall thickening of hearts in rats fed copper-deficient diets was characterized by greater (P < 0.05) LV free wall width, regardless of dietary fat type, and greater intraventricular septum width in the rats fed corn oil. Rats fed the copper-deficient diet with coconut oil + cholesterol had LV chamber volumes that were twofold larger than those of rats fed the copper-deficient diet with coconut oil or corn oil. Copper deficiency reduced LV chamber volume only in rats fed coconut oil + cholesterol. Cardiac LV end diastolic pressure in rats fed copper-deficient diets was twofold larger than in copper-adequate and copper-marginal groups fed corn oil or coconut oil. Hearts from rats fed the copper-deficient diet with corn oil compared with those from rats fed the copper-deficient diet with coconut oil + cholesterol had greater right ventricular (RV) and LV end diastolic pressures, LV pressures and LV and RV maximal rates of positive pressure development. Our data suggest that cardiac adaptations in rats fed copper-deficient diets are influenced by dietary fat type: 1) hearts of rats fed the copper-deficient diet with corn oil were concentrically hypertrophied, whereas cardiac contractility was maintained in the presence of high preload; 2) preload and contractility in hearts of coconut oil-fed rats was greater than cardiac response to cholesterol addition to the coconut oil diet; 3) hearts in copper-deficient rats fed coconut oil + cholesterol exhibited eccentric hypertrophy and ventricular dysfunction.

Copper deficiency alters collagen types and covalent cross-linking in swine myocardium and cardiac valves

Dietary copper deficiency induces alterations of connective tissue metabolism that are associated with lesions in cardiovascular and other organ systems. To determine the impact of copper deficiency on characteristics of collagen in porcine myocardium and cardiac valves, weaned pigs were fed diets with adequate or deficient levels of copper. Although dietary copper did not affect the concentration of collagen in either myocardium or bicuspid valves, the degree of collagen cross-linking, as assessed by the level of hydroxylysylpyridinoline, was lower in both tissues of copper-deficient pigs. Proportions of type III collagen were increased in the left ventricle and bicuspid valves of copper-deficient pigs. Copper deficiency induced extensive remodeling, however, of the collagen fraction of cardiac interstitium. Reduction in left ventricular collagen cross-linking may provide the stimulus for the development of cardiac hypertrophy, which characterizes severe copper deficiency, by increasing the compliance of the ventricular wall. The shift in the phenotypic profile of collagen that is associated with this cardiac hypertrophy indicates synthesis of new collagen, which could affect collagen cross-linking irrespective of copper status.

Cardiac nucleotide levels and mitochondrial respiration in copper-deficient rats

1. Male weanling Long-Evans rats were randomly assigned to either copper-adequate (6.0 mg Cu/kg feed) or copper-deficient (< 1.0 mg Cu/kg feed) diets for a 5 week period. 2. Cardiac ATP levels and energy charges did not differ between the two groups. Levels of NAD and phosphocreatine as well as the sum of pyridine nucleotides were greater in copper-deficient rats compared with copper-adequate rats using HPLC analysis. 3. Mitochondrial respiratory control ratios and oxygen consumption rates from copper-deficient rat hearts were depressed, although ADP:O ratios were similar to copper-adequate rat hearts.

Low and marginal copper intake by postweanling rats: effects on copper status and resistance to carbon tetrachloride hepatotoxicity

Copper feeding studies in rats are generally initiated at weaning. This study examined whether a 6-week feeding of low or marginal Cu levels (0.2 or 2.5 ppm) to rats initially weighing 135 g produced deleterious effects. Controls were fed 8 ppm Cu. Liver Cu-Zn superoxide dismutase activities paralleled Cu intake. Plasma ceruloplasmin activities were very low for both low and marginal Cu consumption. Low but not marginal Cu intake caused a low body weight, high plasma cholesterol level, anemia, cardiac hypertrophy, and a high degree of hepatic plasma membrane injury 24 hours after CCl4 injection (150 microL/kg intraperitoneally [IP]). In summary, low and marginal Cu intakes produced low Cu enzyme activities, while low Cu intake produced pathological symptoms and poor resistance to an oxidative stress.

Cardiac ultrastructural and electrophysiological abnormalities in postweanling copper-restricted and copper-repleted rats in the absence of hypertrophy

Cardiac ultrastructural and functional characteristics were determined in copper-depleted and copper-repleted rats. Male weanling rats were randomized into five groups that were fed either copper-adequate or copper-deficient diets. After 5 wk, one group fed each diet was studied to obtain baseline values. At this time, one copper-adequate postweanling group continued to receive the adequate diet as control, one deficient postweanling group was fed the adequate diet to evaluate the effect of copper repletion and one postweanling adequate group was fed the deficient diet to evaluate copper depletion in relatively older rats. These dietary treatments were continued for six additional weeks. Copper-depleted rats of both ages exhibited significant cardiac ultrastructural pathology and electrocardiogram abnormalities and the postweanling copper-depleted rats exhibited these abnormalities in the absence of hypertrophy and anemia. Increased mitochondrial volume density, disarranged cristae, and nonaligned myofibrils with disturbances at Z-bands were displayed. Additionally, all copper-depleted rats demonstrated fragmented basal laminae at capillary-myocyte interface. Increased QRS amplitude and notching and greater QT intervals were displayed. Copper-repleted rats exhibited some, but not total, reversal of these abnormalities. These results suggest that capillary-myocyte interface changes may play an important role in the developing pathology of copper depletion.

Electrocardiographic activity and cardiac function in copper-restricted rats

The temporal sequence of events leading to cardiac dysfunction during copper restriction in the Long-Evans rat was studied over a 6-week period. Weanling rats were fed either copper-adequate (6 mg Cu/kg diet, n = 25) or copper-restricted (less than 1 mg Cu/kg diet, n = 25) diets for varying periods of time for up to 6 weeks. Beginning at 2 weeks after weaning and weekly thereafter, five rats from each diet were evaluated for cardiac function, and sacrificed, and indicators of copper deficiency were determined on several tissues. Electrocardiograms began showing indications of cardiac disease at Week 3 in the copper-restricted rats, at which time cardiac hypertrophy and other signs of copper deficiency were apparent. Greater QT intervals and QRS amplitudes were observed in copper-restricted rats at various weeks. Peak + and - dP/dt maxs did not differ by diet copper treatment for any of the time intervals studied, nor was any notable difference in developed left ventricular pressure apparent. Hematocrit and liver copper levels were decreased in copper-restricted rat hearts at all weeks. These results suggest that the onset of cardiac dysfunction in copper deficiency is rapid, with both dysfunction and hypertrophy apparent within 3 weeks after copper restriction and when liver copper levels have declined.

Effect of dimethyl sulfoxide on enlarged hearts of copper-deficient rats

The purpose of this study was to examine, by transmission electron microscopy (TEM), the nature of the protective effect of dimethyl sulfoxide (DMSO) on hearts of copper-deficient (CuD) rats. Male, weanling Sprague-Dawley rats were fed, in a two-way design, CuD (0.45 micrograms/g) or copper-sufficient (CuS, 5.4 micrograms/g) diets with or without 5% DMSO in their drinking water. After 28 d, CuD rats showed typical signs of copper deficiency, including reduced liver and heart Cu, enlarged hearts, and anemia. DMSO-treated, CuD rats had lower heart weights and higher hematocrits than CuD rats. DMSO enhanced organ Cu concentrations in CuS, but not in CuD rats. TEM of CuD hearts showed myofibrillar distortion and enlarged, vacuolated mitochondria with fragmented cristae; morphometric measurements indicated an enhanced mitochondrial/myofibrillar ratio (mito/myo), but an increase of both mitochondrial and myofibrillar mass relative to CuS hearts. Compared to CuD hearts, DMSO-treated CuD hearts showed better mitochondrial morphology and myofibrillar organization, as well as a greater mito/myo, but lower mitochondrial and myofibrillar masses. Its function as a hydroxyl radical scavenger indicates that DMSO could protect CuD hearts, in particular their mitochondria, against oxidative damage. However, because measurements of thiobarbituric acid reactive substances were not consistent with this theory, other metabolic mechanisms, direct and indirect, must be examined.

Copper supplementation effects on indicators of copper status and serum cholesterol in adult males

Two 6-wk double-blind studies evaluated the effects of supplements of 2 or 3 mg Cu/d on serum copper, ceruloplasmin, red-blood-cell super oxide dismutase (RBC-SOD), total serum cholesterol, and serum lipoprotein-cholesterol fractions in adult males. Study I had 6 supplemented and 8 placebo subjects, whereas study II had 7 and 6, respectively. Copper supplementation did not appear to affect serum copper levels, RBC-SOD, hematocrit, and ceruloplasmin levels when assayed by radial immunoassay diffusion. Supplementation with 2 mg Cu/d produced an increase in LDL cholesterol and the percentage of cholesterol as LDL at wk 4 compared to the placebo group, and a concomitant decline in VLDL-cholesterol levels and the percentage of cholesterol as VLDL. At wk 6, the percentage of cholesterol as LDL increased and that of cholesterol as VLDL decreased compared to baseline values in the supplemented group. Supplements of 3 mg Cu/d increased hemoglobin levels, ceruloplasmin activity, and serum total-cholesterol levels at wk 6 compared to placebos. Differences in cholesterol may be partly explained by variability in the placebo groups in both studies. Copper supplementation effects on cholesterol deserves further investigation.

Copper deficiency in a genetically hypertensive cardiomyopathic rat: electrocardiogram, functional and ultrastructural aspects

The effect of copper deficiency on cardiac function and structure was studied in a strain of rats (SHHS/Mcc-cp) known to develop cardiac failure as adults. Restriction of dietary copper (less than or equal to 1 mg/kg vs. 6 mg/kg in adequate diets) at weaning in both sexes for a 6-wk period produced cardiac hypertrophy. Male rats developed more severe copper-deficiency symptoms than their female counterparts. In both sexes of copper-deficient rats, there was an increase in cardiac length, width, free ventricular wall thickness and septum thickness. Electrocardiographic tracings revealed greater QRS height among male copper-deficient rats. Heart rate also was substantially reduced in this group. The increased volume of myocardium occupied by mitochondria in the copper-deficient male rats might result in increased electrical resistance that would increase the QRS height; hypertrophy or anemia also could be contributory. Some male copper-deficient rats had prolongation of the QRS in a bundle branch block pattern. Maximal rates of rise and fall for left ventricular pressure were reduced in male copper-deficient rats. The gross histology indicated that this type of heart failure was more concentric than eccentric. The copper-deficient male rat may serve as a useful model for studying the concentric cardiac hypertrophy that occurs in humans.

Myofibrillar, mitochondrial and valvular morphological alterations in cardiac hypertrophy among copper-deficient rats

Histological aspects of Cu-deficient hypertrophied rat hearts were evaluated to determine causal factors. Twenty-four male weanling rats were fed either Cu-adequate (8.0 mg/kg diet) or Cu-deficient (0.4 mg/kg diet) diets until 9 or 11 wk of age. Copper-deficient rats had increased mitochondrial:myofibrillar ratios compared with Cu-adequate rats. Mitochondria were vacuolated. Cristae seemed fragmented and matrix seemed translucent and they tended to distort the myofibrils. Glycogen granules and lipid droplets were more frequently observed in Cu-deficient rats. When the Cu-deficient rats were examined separately, the larger hearts in the older rats had smaller mitochondrial:myofibrillar ratios, but had larger myofibrillar volume densities. Valves from Cu-deficient rats had less connective tissue and seemed fragmented in areas. In 9-wk-old Cu-deficient rats, there was a negative correlation between heart: body weight ratios and bicuspid valve scores, whereas 11-wk-old rats demonstrated the same relationship for tricuspid valves with myofibril volume density. These results suggest that there are two components contributing to cardiac hypertrophy in copper deficient rats: 1) an enlarged mitochondrial area and 2) myofibrillar enlargement. Hematocrit values did not seem to be related to cardiac hypertrophy.

Myofibrillar and nonmyofibrillar myocardial proteins of copper-deficient rats

Myofibrillar and nonmyofibrillar proteins from hearts of copper-adequate (n = 9) and copper-deficient (n = 10) rats were compared. Male weanling Long-Evans rats were fed copper-deficient or copper-adequate diets for 9 wk. Twelve additional rats were fed similar diets and cardiac tissue was evaluated by transmission electron microscopy. Ventricular myocytes were glycerinated and homogenized in 0.1 M KCl and 1.5% Triton X-100, and suspensions were centrifuged at 1100 x g. The supernatant was removed and designated Triton X-100-soluble non-myofibrillar protein, and the pellet was resuspended and recentrifuged several times to obtain myofibrillar protein. Sodium dodecyl sulfate--polyacrylamide gel electrophoresis (SDS-PAGE) analysis was conducted on both protein fractions. Densitometer scans of SDS-PAGE pherograms of myofibrillar protein revealed no significant difference between copper-adequate and copper-deficient groups. Similar analysis of nonmyofibrillar protein revealed a consistent decrease or diminished level of a 23-kDa polypeptide among copper-deficient rat hearts. These results may be consistent with the findings that demonstrated fragementation of mitochondrial cristae and an increased area occupied by mitochondria in copper-deficient rat hearts.

Vitamin and mineral supplementation practices of adults in seven western states

Seven western states (Arizona, California, Idaho, Nevada, New Mexico, Oregon, and Wyoming) were surveyed in 1986 to determine the extent of vitamin/mineral supplementation and dosage levels of single supplements. Questionnaires were mailed to 3,500 individuals. A 57.8% response rate was obtained from the deliverable surveys, with a sample size of 1,730. The sample consisted of 54% women and 46% men and was predominantly white (88.9%). Fifty-four percent of the sample consumed some type of supplement; multiple vitamin/minerals were consumed with the greatest frequency. For single supplements, vitamin C was reported with the greatest frequency (23.1%), followed by some type of calcium supplement (22.5%) and vitamin E (11.1%). More than 80% of the vitamin C users indicated a dosage of 250 mg/day. Most respondents consumed calcium dosages of less than 1,000 mg/day. For vitamin E, 75% of the users consumed more than 200 IU/day. The data suggest that the potential for toxicity due to excess supplementation levels exists in the western states studied.

Zinc supplements and serum lipids in young adult white males

A 12-wk double-blind study was conducted to determine the effect of oral zinc supplementation upon serum total cholesterol, lipoprotein-cholesterol fractions, and serum triglycerides in white males. The subjects were randomly assigned to one of three treatment groups and consumed either a placebo tablet (n = 9), 50 mg Zn/d (n = 13), or 75 mg Zn/d (n = 9) as Zn gluconate. Serum total cholesterol, low-density-lipoprotein (LDL) cholesterol, very-low-density-lipoprotein (VLDL) cholesterol, and triglycerides were not affected by Zn supplements. However, serum high-density-lipoprotein (HDL)-cholesterol levels in subjects assigned to the 75 mg Zn/d group were significantly lower at weeks 6 and 12 than those for the placebo group and lower at weeks 6, 8, and 12 than at baseline; subjects assigned to the 50 mg Zn/d group had lower serum HDL-cholesterol levels at week 12 than did the placebo group and lower at week 12 than at base line.

Fatty acids of liver, cardiac and adipose tissues from copper-deficient rats

The effect of copper deficiency on liver, cardiac and adipose fatty acids was studied in the Long-Evans rat. Rats were fed diets adequate in copper (8.5 mg Cu/kg diet, group AC, n = 10) or with no added copper (0.4 mg Cu/kg diet, group NC, n = 9) or were pair-fed an adequate copper diet in amounts eaten by group NC rats (group PF, n = 10), from weaning until 8 wk thereafter. Group NC rats exhibited typical copper deficiency signs such as decreased body weight, hematocrit and liver copper levels but increased heart/body weight ratios. Adipose and cardiac triglycerides of group NC rats had greater 18:0 to 18:1n-9 ratios. All tissues in group NC rats had higher levels of longer-chain polyunsaturated fatty acids in triglycerides than those in AC or PF rats. Specifically, the following triglyceride fatty acids were in greater concentration in NC rats than in AC or PF rats: for liver, 18:2n-6, 22:5n-6, 22:5n-3 and 22:6n-3; for cardiac, 20:3n-6, 20:4n-6 and 22:5n-6. Liver phospholipids had lower levels of 20:4n-6 in NC rats than in AC or PF rats. These results suggest that copper deficiency results in the accumulation of both n-3 and n-6 longer-chain polyunsaturated fatty acids in triglycerides of various tissues.

Hair minerals and diet of Prader-Willi syndrome youth

This study investigated the relationships between mineral elements and Prader-Willi syndrome (PWS) and determined which minerals, if any, separated a group of PWS individuals (N = 19) from a non-PWS mentally retarded control group (N = 60). The PWS group had significantly raised hair magnesium levels and significantly lower hair silicon levels than controls. The PWS group was also elevated in hair calcium, magnesium, and copper in relation to laboratory standards, while their hair silicon, chromium, and lithium levels were deficient in relation to laboratory norms. Discriminant function analysis revealed that by using 16 hair minerals subjects could be correctly classified as PWS or non-PWS with 89.5% and 95.0% accuracy, respectively. It is concluded that continuing research is needed to study the relationship between mineral element patterns and PWS.

Aluminum ingestion and behavior in the Long-Evans rat

A variety of behaviors was measured in adult Long-Evans male rats fed ground rat chow containing either no added aluminum, low aluminum (1500 mg/kg), moderate aluminum (2500 mg/kg), or high aluminum (3500 mg/kg). There were no effects of aluminum on either body weight or mouse killing. There was an inverse relationship between brain aluminum and open-field activity. Elevated brain aluminum was correlated with relatively poor performance on a single-trial passive-avoidance task and on a visual discrimination with reversal task.

Effect of copper deficiency and Sodium intake upon liver lipid and mineral composition in the rat

The effect of copper and sodium intake upon liver cholesterol concentrations, fatty acid profile, and mineral concentrations were studied in the Long-Evans rat. Forty-eight male weaning rats were divided into three groups of 16 each and fed a semipurified diet containing either 0, 3, or 8 mg of added copper/kg of diet. At 100 d of age, half of the animals in each group were given 1% NaCl as drinking water and the other half was given deionized-distilled water for 12 wk. Copper deficiency in rats produced elevations in liver palmitate and oleate concentrations, but decreases in linoleate concentrations. The ratio of oleate:stearate was higher in copper deficient rats. Liver copper levels were decreased, but liver iron concentrations were elevated in copper deficient rats. Sodium intake did not have an effect on any of the parameters studied. These results suggested that dietary copper deficiency alters both liver mineral and fatty acid composition.

Postweaning copper restriction and behavior in the Long-Evans rat

A variety of behaviors was assessed in Long-Evans male rats placed on either a low copper diet, a marginal copper diet, or an adequate copper diet at weaning. Rats in the low copper group had slightly, but significantly, enlarged hearts and gained less weight than rats fed diets containing higher copper levels. Treatment effects were not detected in measurements of muricide, open-field activity, water intake, shock sensitivity, and shock avoidance and memory.

Blood pressure in young adults as influenced by copper and zinc intake

The relationship of copper and zinc status with blood pressure in young adults was studied (N=59). Copper and zinc status was assessed through analysis of serum, urine, hair, and diet records. Males (N=27) had greater systolic and pulse pressures than females (N=32). Multiple regression analysis suggested that males and higher caloric and dietary copper intakes were the predominant factors associated with higher systolic and diastolic pressures, whereas higher dietary zinc intakes were associated with lower pressures. Higher urine zinc excretion rates and serum zinc concentrations were associated with higher diastolic pressures. The sex variable was the strongest factor affecting pulse pressures, with males having higher pulse pressures. Serum zinc concentrations had an inverse relationship to pulse pressures. The data suggest that the weight/height index and age had a low association with blood pressure in this normotensive sample.