Sodium Bicarbonate Supplementation Research Articles

Sodium Bicarbonate Improves Swimming Performance

Sodium bicarbonate ingestion has been shown to improve performance in single-bout, high intensity events, probably due to an increase in buffering capacity, but its influence on single-bout swimming performance has not been investigated. The effects of sodium bicarbonate supplementation on 200 m freestyle swimming performance were investigated in elite male competitors. Following a randomised, double blind counterbalanced design, 9 swimmers completed maximal effort swims on 3 separate occasions: a control trial (C); after ingestion of sodium bicarbonate (SB: NaHCO3 300 mg . kg (-1) body mass); and after ingestion of a placebo (P: CaCO3 200 mg . kg (-1) body mass). The SB and P agents were packed in gelatine capsules and ingested 90 - 60 min prior to each 200 m swim. Mean 200 m performance times were significantly faster for SB than C or P (1 : 52.2 +/- 4.7; 1 : 53.7 +/- 3.8; 1 : 54.0 +/- 3.6 min : ss; p < 0.05). Base excess, pH and blood bicarbonate were all elevated pre-exercise in the SB compared to C and P trials (p < 0.05). Post-200 m blood lactate concentrations were significantly higher following the SB trial compared with P and C (p < 0.05). It was concluded that SB supplementation can improve 200 m freestyle performance time in elite male competitors, most likely by increasing buffering capacity.

Influence of Varying Level of Sodium Bicarbonate on Milk Yield and Its Composition in Early Lactating Nili Ravi Buffaloes

Influence of varying level of sodium bicarbonate (SB) supplementation on milk yield and its composition was examined in a randomized complete block design in early lactating Nili Ravi buffaloes during summer. Four iso-nitrogenous and iso-caloric diets were formulated. The diet 0B contained 0 while LB, MB and HB diets contained 0.50, 1.0 and 1.50% SB levels, respectively. The diets were randomly allotted to twenty buffaloes, five in each group. A linear increase in nutrient and water intake was recorded with increasing SB level. Buffaloes fed MB and HB diets showed higher nitrogen balance than those fed 0B and LB diets. A significant increase in blood pH and serum bicarbonate was noticed with increasing SB level. Urine pH increased significantly with increased SB level. A linear increase in milk yield was also noticed with increasing SB level. Milk fat% increased significantly in buffaloes fed MB and HB diets compared with those fed 0B and LB diets. Buffaloes fed HB diet had higher conception rate and less services per conception than those fed 0B diet. This study indicated that a high SB diet not only increased dry matter and water intake, milk yield, milk fat% but also increased conception rate in early lactating buffaloes during summer.

Sodium Bicarbonate Supplementation Improves 200 m Freestyle Performance in Elite Male Swimmers

Sodium Bicarbonate Supplementation Improves 200 m Freestyle Performance in Elite Male Swimmers

Long-Term Oral Sodium Bicarbonate Supplementation Does Not Improve Serum Albumin Levels in Hemodialysis Patients

Metabolic acidosis, a frequent event in hemodialysis patients, has been implicated as a potential cause of protein-energy malnutrition. Unfortunately, correction of metabolic acidosis by means of high bicarbonate concentration in the dialysate does not seem to lead to significant changes in nutritional parameters. The project was a single-arm, open-label, 12-month pilot study at a university-based tertiary care center aimed at evaluating whether correction of metabolic acidosis through long-term oral sodium bicarbonate supplementation improves serum albumin levels and other nutritional parameters in patients undergoing maintenance hemodialysis. Twenty highly acidotic hemodialysis patients patients were invited to consume an oral supplementation of sodium bicarbonate (1 g, thrice daily), for 12 months. Patients were followed at baseline and every month, until month 12. At each follow-up visit, dry body weight, BMI, blood pressure, presence of edema, venous bicarbonate, and serum albumin were measured. Total lymphocyte count, fasting total cholesterol and C-reactive protein were assessed every 2 months. At baseline and at 12 months, the subjective global assessment of nutritional status and the protein equivalent of nitrogen appearance normalized to actual body weight were determined. Plasma bicarbonate level rose from 18.1 ± 2.7 to 22.1 ± 4.5 mmol/l after 10 months (p = 0.001). Mean serum albumin levels were 3.8 ± 0.2 mg/dl at baseline and 3.9 ± 0.2 at the end of the study. Repeated measure ANOVA showed that there was no significant effect of bicarbonate treatment on serum albumin levels (p = 0.29), dry weight (p = 0.1), serum total cholesterol (p = 0.97), total lymphocyte count (p = 0.69), or C-reactive protein (p = 0.85). Mean subjective global assessment score was 4.53 ± 0.37 at baseline and 4.58 ± 0.54 at 12 months (p = 0.1). Mean nPNA (g/kg/day) was 0.86 ± 0.05 at baseline and 0.85 ± 0.08 at month 12. The present study demonstrates that long-term oral sodium bicarbonate at the dose of 1 gram thrice daily has no significant effect on nutritional status of HD patients.

Comparison of lactated Ringer’s solution and 0.9% saline in the treatment of rhabdomyolysis induced by doxylamine intoxication

Objective: To compare the effectiveness and side effects of lactated Ringer’s solution (LR) and 0.9% saline (NS) in the treatment of rhabdomyolysis induced by doxylamine intoxication. Methods: In this 15-month-long...

Distal renal tubular acidosis a rarely diagnosed cause of failure to thrive: A report of three cases

SUMMARYThree cases of distal renal tubular acidosis aged between 6 - 12weeks are described. The presenting features included lethargy, refusal to feed, marked periodic respiration, vomiting and recurrent episode of unexplained metabolic acidosis. A constant feature was failure to thrive despite caloric intake in excess of normal requirements. The diagnosis of distal renal tubular acidosis was based on a urine PH&gt;5.5 in freshly voided urine despite the presence of metabolic acidosis. All the babies responded promptly to sodium bicarbonate supplement. An increased suspicion of distal tabular acidosis in the evaluation of children in early infancy for failure to thrive is therefore advised.

Effect of dietary sodium bicarbonate supplementation on carcass and meat quality of high concentrate fed lambs

Effect of sodium bicarbonate (NaHCO 3) in high concentrate fed lambs was studied on carcass and meat quality characteristics. Twenty-four weaner (90 days old) Malpura lambs divided into four equal groups (G1, G2, G3 and G4) were fed basal diet (25:75 roughage:concentrate, G1) or basal diet supplemented with 0.75% (G2), 1.50% (G3) and 2.25% (G4) sodium bicarbonate for 90 days. Lambs were slaughtered for carcass and meat quality evaluation. Longissimus dorsi was collected and analysed for meat quality traits. Pre-slaughter weight was higher ( P < 0.05) in sodium bicarbonate-supplemented (G2, G3, and G4) groups than in the control group (G1). The muscular development as indicated by loin eye area was higher ( P < 0.05) in the treatment groups (G2, G3 and G4) as compared to control. There were no significant differences ( P > 0.05) in visceral fat contents in lambs of control and treated groups. The carcass fat content was lesser ( P < 0.05) in treated lambs than control groups. In leg, the lean content was more ( P < 0.05) in treated groups (G3 and G4) as compared to control (G1). Cook loss% was higher ( P < 0.05) in treated groups as compared to control. There was no significant difference ( P > 0.05) in shear force value of meat from control or treated lambs. It is concluded from the study that dietary supplementation of sodium bicarbonate in high concentrate diets did not exert much influence on carcass and meat quality characteristics. However, the dressing yield improved and total separable carcass fat was reduced by supplementing buffer to high concentrate fed lambs.

Effects of sodium bicarbonate and yeast on productive performance and carcass characteristics of light-weight lambs fed finishing diets

This experiment was conducted to study productive performance and carcass characteristics of finishing lambs fed diets containing yeast culture (YC) and/or sodium bicarbonate (SB). Twenty male Pelibuey lambs, weighing 11.4 kg, were assigned to one of four groups according to a completely randomized design, with a 2 × 2 factorial arrangement of treatments. Each group received a basal diet with one of the following four treatments: (1) no additives (NA); (2) 0.12% yeast culture (YC; Yea Sacc ® 1026; All-Tech, Lexington, Kentucky) containing 2.8 × 10 4 cfu of yeast/g; (3) 0.5% sodium bicarbonate (SB); and (4) both, 0.12% YC and 0.5% SB. Lambs were individually confined to 1.5 m 2 metabolic cages. Dry matter (DM) intake, on a live weight basis, was not different among treatments ( P > 0.05) during the entire 60-day period. However, when expressed on an empty body weight basis, SB in the diet significantly increased ( P < 0.05) DM intake. Similarly, weight gain was not affected ( P > 0.05) by the inclusion of YC or SB. Although feed efficiency was not affected ( P > 0.05) by YC, more feed was required per unit gain when SB was added to the ration ( P < 0.05). Cold and hot carcass weights (kg) were not different ( P > 0.05) among treatments. Full gastrointestinal tract weight was not affected by YC or SB supplementation. Neither YC or SB affected marbling score, external fat, or longissimus muscle (ribeye) area. However, SB increased ( P < 0.05) degree of finishing of lamb carcasses. No effect of YC or SB in the diet was observed on weight of skin, liver, lungs, testicles or blood. Heart weight was greater ( P < 0.05) for lambs consumed diets with YC. First and second yield carcass grade were not affected ( P > 0.05) by YC or SB.

Assessment the Impacts of Dietary Electrolyte Balance Levels on Laying Performance of Commercial White Layers

Two experiments were conducted to test whether egg performance and egg shell quality during peak egg production are affected by the diets supplemented with NaHCO or K CO . In experiment 1 four 3 2 3 diets were formulated using different inclusions of NaCl, NaHCO and K CO to give the dietary electrolyte 3 2 3 balances (DEB) as 176, 204, 225 and 242 mEq/kg, and fed to laying hens from 22 weeks to 30 weeks of age. In experiment 2, two diets were formulated to obtain DEB of 186 and 208, and fed to the same strain from 31 to 39 weeks of age. Egg production, egg shell quality, feed intake, egg mass and feed conversion ratio were not significantly affected by the diets of various DEB (P>0.05). In conclusion, the results suggested that there was no need for the supplementation of sodium bicarbonate and or potassium carbonate into practical laying hen diets during peak egg production.

Effect of Oral Sodium Bicarbonate Supplementation on Interdialytic Weight Gain, Plasma Sodium Concentrations and Predialysis Blood Pressure in Hemodialysis Patients

Background: Correction of metabolic acidosis in dialysis patients should be considered of paramount importance. However, consuming sodium bicarbonate tablets during the interdialytic interval to reach predialysis bicarbonate levels of 23–24 mmol/l is not widespread due to the fear of greater interdialytic weight gain and fluid overload. For this reason we investigated in a cross-sectional and in an interventional study the effect of oral sodium bicarbonate supplementation on body weight gain, plasma sodium concentrations and predialysis blood pressure in a group of stable uremic patients on regular hemodialysis (HD) treatment. Study Design: 110 patients (67 men, 43 women), mean age 67 ± 15 (range 22–89) years, on regular chronic HD treatment for 6–372 (median 48) months were studied. 70 patients were on regular oral bicarbonate supplementation for at least 4 weeks (group A), 40 patients were not on oral bicarbonate supplementation (group B). The following parameters were recorded: dry body weight (DBW), interdialytic weight gain (IWG), body mass index (BMI), plasma sodium (Na), serum pH, serum bicarbonate (sBic), K_t/V, normalized protein catabolic rate (PCRn), predialysis systolic (SBP) and diastolic (DBP) blood pressure, and bicarbonate therapy (g/day). 18 patients not on oral bicarbonate supplementation with sBic levels ≤20 mmol/l were started on oral bicarbonate therapy and were prospectively followed in the context of an interventional study of correction of chronic metabolic acidosis. The same parameters were recorded before (pre) and after (post) 4 months of oral bicarbonate supplementation. Results:Serum pH and sBic concentrations were significantly higher in patients in group A compared to patients in group B (pH 7.37 ± 0.02 group A vs. 7.33 ± 0.02 group B: p <0.001: sBic 23.8 ± 1.4 group A vs. 20.9 ± 1.4 group B: p < 0.0001). Age, DBW, BMI, IWG, SBP, DBP, Na, K_t/V and PCRn did not differ between groups. The mean daily dose of oral sodium bicarbonate administered to patients in group A was 1.9 ± 0.9 (range 1–5, median 2) g/day. Also in the 18 patients who started bicarbonate treatment, a significant increase in serum pH and sBic concentrations and a significant reduction in PCRn were observed. No significant change in DBW, IWG, SBP, DBP and Na concentrations after 4 months of treatment was found. Conclusions: Our data show that in stable uremic patients on regular HD treatment, oral daily administration of sodium bicarbonate is effective in correcting mild-moderate chronic metabolic acidosis, and does not cause increased interdialytic body weight gain, different plasma sodium concentrations and different systolic-diastolic blood pressure levels compared to patients not on oral sodium bicarbonate supplementation.

Effect of dietary sodium bicarbonate supplementation on the toxicokinetics of ochratoxin A in pigs

The mycotoxin ochratoxin A (OA) is regarded as a causative agent for endemic nephropathy in farm animals and humans. Reabsorption of OA along the nephron results from nonionic diffusion and by carrier-mediated mechanisms indicating that urine alkalinization may help to accelerate OA excretion and thus reduce its toxicity. The aim of the present study was to investigate the effect of a dietary sodium bicarbonate (NaHCO3) supplementation as a means to increase urinary pH on the systemic availability and excretion of OA in pigs. Dietary supplementation of 2% NaHCO3 increased urinary pH (5.7±0.2 to 8.3±0.1) and daily urine volume (1108±276 to 2479±912ml) significantly. The systemic availability of OA and its dechloro-analog Ochratoxin B (OB) in the NaHCO3 group calculated as the area under the serum concentration-time curve (AUC) was reduced to 75 and 68%, respectively, of the control (P<0.05). This effect was mainly due to an accelerated elimination of OA and OB in the urine. The faster renal elimination might be explained by a reduced reabsorption of the ochratoxins by nonionic diffusion, and other H(+)-dependent mechanisms. Thus, urinary alkalinization might be an efficient means to partially reduce the toxic effects and carry-over of OA in pigs.

Alkalinization of Urinary pH Accelerates Renal Excretion of Ochratoxin A in Pigs

The mycotoxin ochratoxin A (OA) is a cause of endemic nephropathy in farm animals and humans. Reabsorption of OA along the nephron results from nonionic diffusion and by carrier-mediated mechanisms, indicating that urine alkalinization may help to accelerate OA excretion and thus reduce its toxicity. The aim of the present study was to investigate the effect of a dietary sodium bicarbonate supplementation as a means of increasing urinary pH on the systemic availability and excretion of OA in pigs. Dietary supplementation of 2% sodium bicarbonate significantly increased urinary pH (5.7 +/- 0.2 to 8.3 +/- 0.1) and daily urine volume (1108 +/- 276 to 2479 +/- 912 mL). The systemic availability of OA and its dechloro-analog, Ochratoxin B (OB), calculated as the area under the curve (AUC) was reduced to 75 and 68%, respectively, of the control group (P < 0.05). This effect was due mainly to an accelerated elimination of OA and OB in the urine. The faster renal elimination may be due to reduced reabsorption of the ochratoxins by nonionic diffusion, and other H(+)-dependent mechanisms. Thus, urinary alkalinization may be an efficient means to partially reduce the toxic effects of OA in pigs.

Effect of sodium bicarbonate supplementation on ruminal fluid pH, feed intake, nutrient utilization and growth of lambs fed high concentrate diets

This experiment studied effects of increasing levels of dietary sodium bicarbonate (NaHCO 3) on ruminal fluid pH, feed intake, nutrient utilization, body weight (BW) gain and feed conversion efficiency of lambs fed high concentrate diets offered ad libitum. Forty weaner (90 days) Malpura lambs, divided into four equal groups, were fed levels of NaHCO 3: 0 (control), 7.5, 15.0, or 22.5 g NaHCO 3 per of kg feed DM. The feeding experiment was for 91 days. Pala ( Zizyphus nummularia) leaves were used as the forage and the diet contained about 25% high glucosinolate mustard meal. Increasing supplementation of NaHCO 3 increased ruminal fluid pH linearly ( P<0.05), in the range of 6.03–6.44 and linearly ( P<0.06) increased trend to NDF and ADF digestibilities. Digestibility of dry matter, organic matter and gross energy did not differ among the treatments. Average daily gain showed linear and quadratic increases with increasing NaHCO 3 and were highest in lambs supplemented with 15 g NaHCO 3. No differences in daily intake of metabolizable protein occurred, whereas, digestible and metabolizable energy intake per unit live weight gain was higher in NaHCO 3 supplemented lambs. For all treatments, lambs were in positive N balance and NaHCO 3 supplementation did not alter N retention, calcium and phosphorus utilization, and blood parameters. Incorporation of NaHCO 3 to a high concentrate diet fed to weaner lambs improved growth by 35% at 15.0 g NaHCO 3 by improving feed intake and fiber digestibility.

Effect of dietary sodium bicarbonate supplementation on fermentation characteristics and ciliate protozoal population in rumen of lambs

Effects of sodium bicarbonate (NaHCO 3) inclusion on rumen fermentation characteristics and ciliate protozoal population in high concentrate-fed lambs were studied. Twenty-four weaner (90 days old) Malpura lambs divided into four equal groups (G1, G2, G3 and G4) were fed basal (25:75 roughage and concentrate) diet (G1) or basal diet supplemented with 0.75% (G2), 1.50% (G3) and 2.25% (G4) sodium bicarbonate for 90 days. Daily dry matter (DM) intake and digestibility of organic matter (OM), crude protein (CP), gross energy and plane of nutrition were similar in all the groups while cellulose digestibility was higher in G4 than in G2 and G1. Ruminal pH increased ( P<0.05) with increasing levels of dietary sodium bicarbonate. Concentrations of total volatile fatty acids (TVFA), total nitrogen and trichloroacetic acid-precipitable nitrogen (TCA-ppt.-N) were higher while ammonia nitrogen was lower in the rumen fluid of G4 and G3 than in G2 and G1. The number of total protozoa, Isotricha, Dasytricha, large and small spirotrichs were higher ( P<0.01) in the rumen of G4 and G3 than in G2 and G1. Total live weight gain and average daily gain were also higher in lambs supplemented with sodium bicarbonate. It is concluded that sodium bicarbonate inclusion at the rate of 1.50% of total ration increased cellulose digestibility, ciliate protozoal number, ruminal pH and total nitrogen concentration resulting in improved growth of lambs maintained on high concentrate diet.

Effect of the correction of metabolic acidosis on nutritional status in elderly patients with chronic renal failure

Background: Metabolic acidosis (MA) is a frequent complication in advanced chronic renal failure (CRF). Currently, there is good evidence that MA contributes to malnutrition in CRF patients. Methods: We evaluated the effect of correcting MA on nutritional status after 6 months of oral sodium bicarbonate supplementation in 18 patients aged 73 ± 6 years with CRF to maintain serum bicarbonate levels at 24 ± 2 mmol/L. The following parameters were measured: dietary record, energy intake, dietary protein intake (DPI), mini-nutritional assessment (MNA), serum albumin level, prealbumin level, prognosis inflammatory and nutritional index (PINI), and protein catabolic rate (nPCR). Results: No significant changes in body weight or systolic and diastolic blood pressure were observed. Serum albumin and prealbumin levels showed a significant increase. nPCR decreased significantly. DPI, energy intake, PINI, and MNA score did not change significantly. No patient reported side effects or fluid retention during the study. Conclusion: Correction of MA improves serum albumin and prealbumin concentration, and it is not associated with any significant change in DPI, but induces a decrease in nPCR values. Whereas nPCR may provide an index of protein catabolism, it does not differentiate between dietary sources of protein or net catabolism of endogenous proteins. In the absence of dietary changes, the decrease in nPCR values may be attributed to a decrease in whole body protein degradation. © 2002 by the National Kidney Foundation, Inc.

The effect of consumption of foods that differ in energy density and/or sodium bicarbonate supplementation on subsequent diet selection in sheep

The short-term consumption of foods that differed in energy density (ED) and/or NaHCO3 supplementation, on subsequent food intake and diet selection in sheep were measured. Thirty sheep weighing 35·9 (SD 2·89) KG WERE USED. TWO FOODS WERE FORMULATED: H HAD 11 AND L HAD 8 MJ METABOLIZABLE ENERGY/KG FRESH MATTER. FOUR FURTHER FOODS WERE FORMULATED BY ADDING EITHER 40 G NAHCO3/KG OR 16·5 G NACL/KG TO FOODS H AND L. NACL WAS ADDED TO GIVE THE SAME NA CONCENTRATION AS WITH 40 G NAHCO3/KG TO CONTROL FOR ANY EFFECTS OF NA PER SE. IN A PRELIMINARY TEST, IT WAS FOUND THAT A 2 H CONSUMPTION OF FOOD H SUPPLEMENTED WITH NAHCO3 COULD BUFFER POTENTIAL IMPACT ON THE RUMEN ENVIRONMENT OF SUBSEQUENT CONSUMPTION OF FOOD H ALONE (AS JUDGED BY RUMEN PH AND ACID-BUFFERING CAPACITY); HOWEVER, IT WAS NOT AS EFFECTIVE AS THE CONSUMPTION OF FOOD L ALONE IN DOING SO. EACH FOOD TREATMENT WAS OFFERED TO ONE OF SIX GROUPS (N 5) FOR 2 H FOLLOWING 16 H OF FOOD DEPRIVATION. SHEEP WERE THEN OFFERED A CHOICE BETWEEN H AND L FOR A FURTHER 6 H. SUPPLEMENTING H OR L WITH EITHER NAHCO3 OR NACL HAD NO SIGNIFICANT EFFECT ON EITHER INTAKE OR DIET SELECTION. ED SIGNIFICANTLY (P&lt;0·01) AFFECTED INTAKE DURING THE 2 H SINGLE FEEDING PERIOD, WITH SHEEP OFFERED H OR L CONSUMING 540 AND 663 (sed 37) g respectively, but had no effect on subsequent intake during the choice period. During the choice period all sheep showed a preference for food H, but sheep previously offered L selected significantly more H (0·873 g/g) than sheep previously offered H (0·544 (sed 0·028) g/g; P&lt;0·001). It is concluded that short-term consumption of foods that differ in ED, and hence in their potential impact on the rumen environment, significantly affects subsequent diet selection. This is in agreement with the hypothesis that ruminant animals select a diet to help maintain the rumen environment within a certain physiological range. Food H with 40 g NaHCO3 added/kg may not have been sufficient to affect subsequent diet selection. It is suggested that larger, rather than smaller, changes in the rumen environment achieved through previous feeding should be expected to alter subsequent diet selection.

The effect of consumption of foods that differ in energy density and/or sodium bicarbonate supplementation on subsequent diet selection in sheep.

The short-term consumption of foods that differed in energy density (ED) and/or NaHCO3 supplementation, on subsequent food intake and diet selection in sheep were measured. Thirty sheep weighing 35.9 (sd 2.89) kg were used. Two foods were formulated: H had 11 and L had 8 MJ metabolizable energy/kg fresh matter. Four further foods were formulated by adding either 40 g NaHCO3/kg or 16.5 g NaCl/kg to foods H and L. NaCl was added to give the same Na concentration as with 40 g NaHCO3/kg to control for any effects of Na per se. In a preliminary test, it was found that a 2 h consumption of food H supplemented with NaHCO3 could buffer potential impact on the rumen environment of subsequent consumption of food H alone (as judged by rumen pH and acid-buffering capacity); however, it was not as effective as the consumption of food L alone in doing so. Each food treatment was offered to one of six groups (n 5) for 2 h following 16 h of food deprivation. Sheep were then offered a choice between H and L for a further 6 h. Supplementing H or L with either NaHCO3 or NaCl had no significant effect on either intake or diet selection. ED significantly (P<0.01) affected intake during the 2 h single feeding period, with sheep offered H or L consuming 540 and 663 (sed 37) g respectively, but had no effect on subsequent intake during the choice period. During the choice period all sheep showed a preference for food H, but sheep previously offered L selected significantly more H (0.873 g/g) than sheep previously offered H (0.544 (sed 0.028) g/g; P<0.001). It is concluded that short-term consumption of foods that differ in ED, and hence in their potential impact on the rumen environment, significantly affects subsequent diet selection. This is in agreement with the hypothesis that ruminant animals select a diet to help maintain the rumen environment within a certain physiological range. Food H with 40 g NaHCO3 added/kg may not have been sufficient to affect subsequent diet selection. It is suggested that larger, rather than smaller, changes in the rumen environment achieved through previous feeding should be expected to alter subsequent diet selection.

Diet selection of sheep: sodium bicarbonate, but not the offering of hay, modifies the effect of urea on diet selection

AbstractThe hypotheses tested were that the expected preference of sheep for a food with adequate rumen degradable protein (RDP) supplemented with urea would be reduced both by the addition of a buffer (sodium bicarbonate (SB)) and by offering ad libitum access to hay. A control food (C), calculated to be adequate in its ratio of effective RDP to fermentable metabolizable energy (fME), was formulated. Other foods were made by adding 12·5 (U1) or 25 (U2) g urea per kg fresh matter (FM) to C and 20 g SB per kg FM to C, U1and U2. The acid buffering capacity (ABC) of each food was measured in vitro. The experiment consisted of two successive periods, each of 4 weeks. Ninety-eight female, Texel ✕ Greyface sheep were randomly allocated to 14 groups each with seven animals. Groups 1 to 6 were offered one of: C, U2, C + SB, U2+ SB, C with hay or U2with hay throughout the experiment. Groups 7 to 10 were offered the choices of C v. U1or C v. U2, either with or without hay in a change-over design; animals that received hay during period 1 (groups 8 and 10) did not do so during period 2 and vice versa (groups 7 and 9). Groups 11 to 14 (no. = 7) were offered the choices of C v. U1or C v. U2, either with or without SB supplemented to both foods, in a change-over design. Adding either urea, or SB, or both to C had no effects on intake or live-weight gain when offered alone. Both supplements significantly (P 0·001) increased the ABC of food C. Throughout the experiment hay consumption was very low (overall mean: 23 (s.e. 2·5) g hay per sheep day). Offering hay caused no change in the preference for the urea-supplemented foods. Sheep offered the choices C v. U1or C v. U2, with neither hay nor SB, selected 0.466 (s.e. 0·036) and 0.588 (s.e. 0·025) kg/kg total food intake (TFI) of U1and U2respectively. The proportions of the urea-supplemented foods were significantly reduced (P 0.01) by SB supplementation: to 0.348 (s.e.0·045) and 0·406 (s.e.0·059) kg/kg TFI of U1and U2respectively. The effect of SB addition on the diet selection of sheep could be due to its buffering properties. When SB is added to both foods the need for urea to be used as a buffer is reduced with a consequent decrease in the proportion selected as the urea-supplemented food. Effects of diet on buffering may override other diet selection objectives, such as the avoidance of an excess intake of RDP.

Effects of sodium bicarbonate supplementation on axial and peripheral bone mass in rats on strenuous treadmill training exercise.

We observed the effects of sodium bicarbonate supplement on bone mass in rats on strenuous treadmill training. Sixty female Wistar rats (93-days-old; mean initial weight 261 +/- 16 g) were studied. One group of 15 rats was killed at the beginning of the experiments (basal control group), while another group of 15 rats was not manipulated (Exer-NaB-). Another group of 15 rats was exercised but did not receive sodium bicarbonate (Exer+NaB-), while the final group of 15 rats exercised and received sodium bicarbonate (Exer+NaB+) at a dose of 0.05 mg/kg/day, administered by esophageal catheter on exercise days. These rats were killed at the end of 11 weeks. Femoral and vertebral length, weight, and bone mineral content (BMC) and density (BMD) were measured. According to ANOVA with the Tukey-Kramer test, femur length and weight, vertebral weight, femur BMC and BMD, vertebral BMC and BMD and the ratio between femur and vertebral BMC and final body weight, and plasma bicarbonate were lower in the basal control and Exer+NaB- groups than in the two other groups (P < 0.005-0.0001). Overall, there was a positive correlation between femur and vertebral BMC and femur BMC and length (P < 0.0001 for all). Only in the Exer+NaB- group was there a positive association between plasma bicarbonate levels and femur length (r = 0.78; P < 0.0005). Our study demonstrates the adverse effects of strenuous exercise on bone, and the usefulness of sodium bicarbonate supplements in preventing and minimized these effects.

Direct Effect of the Correction of Acidosis on Plasma Parathyroid Hormone Concentrations, Calcium and Phosphate in Hemodialysis Patients: A Prospective Study

Background: Metabolic acidosis contributes to renal osteodystrophy and together with hyperphosphatemia, hypocalcemia and altered vitamin D metabolism may result in increased levels of intact parathyroid hormone (iPTH) and metastatic calcifications. However, the impact of the correction of metabolic acidosis on iPTH levels and calcium-phosphate metabolism is still controversial. Study Design: The effects of the correction of metabolic acidosis on serum concentrations of iPTH, calcium (Ca), phosphate (PO₄) and alkaline phosphatase were prospectively studied. Twelve uremic patients on maintenance hemodialysis (HD) for 49 months (median; range 6–243 months) with serum bicarbonate levels ≤20 mmol/l were studied before and after 3 months of oral sodium bicarbonate supplementation. Predialysis serum bicarbonate, arterial pH, ionized calcium, plasma sodium, plasma potassium, serum creatinine, hemoglobin, K_t/V, postdialysis body weight, predialysis systolic and diastolic blood pressure were also evaluated before and after correction. Results: Serum bicarbonate levels and arterial pH increased respectively from 19.3 ± 0.6 to 24.4 ± 1.2 mmol/l (p < 0.0001) and 7.34 ± 0.03 to 7.40 ± 0.02 (p < 0.001). iPTH levels decreased significantly from 399 ± 475 to 305 ± 353 pg/ml (p = 0.026). No changes in total serum Ca, plasma PO₄, serum akaline phosphatase, K_t/V, serum creatinine, hemoglobin, body weight, predialysis systolic and diastolic blood pressures were observed. iCa decreased significantly. Conclusions: Our study demonstrates that the correction of metabolic acidosis in chronic HD patients reduces iPTH concentrations in HD patients with secondary hyperparathyroidism possibly by a direct effect on iPTH secretion.