Mmol Ca Research Articles

Adsorption of calcium ions by graft copolymer of acrylic acid on biopolymer chitin

The graft copolymer of acrylic acid on biopolymer chitin, with 45% grafting efficiency, was used to study the effect of the carboxylic group of the graft copolymer on the metal binding ability of calcium ions in aqueous solution as a function of pH, contact time and metal concentration. The adsorption equilibrium data correlate well with the Langmuir isotherm equation. The maximum adsorption capacities of graft copolymer and chitin were found to be 0.500 ± 0.013 and 0.195 ± 0.005 mmol Ca 2+ g −1 , respectively, suggesting the effective participation of the carboxylic group in Ca 2+ adsorption. The poly(acrylic acid)- grafted chitin is promising as a polymeric matrix to be used in the preparation of new glass ionomer cements.

Calcium bioavailability from a calcium- and sulfate-rich mineral water, compared with milk, in young adult women

Some mineral waters have a high calcium content and may contribute a significant part of the human daily requirements. Calcium bioavailability from a calcium- and sulfate-rich mineral water (CS-W) containing 11.2 mmol Ca/L (467 mg/L) was compared with that from milk in nine healthy young women. Calcium absorption was measured in the fasting state with a dual-label stable-isotope technique. Fractional absorption rates from milk and CS-W were 25.0 +/- 6.7% and 23.8 +/- 4.8% (means +/- SD), respectively, and did not differ significantly (P = 0.05). Urine was collected for 36 h after the administration of the oral stable isotope while the subjects consumed a controlled diet and a quantity of milk or CS-W providing 25 mmol (1000 mg) Ca. No significant difference was found in the excretion of calcium, nor in the excretion of the two stable isotopes. Mean urinary sulfate excretion was significantly increased by 35% when the CS-W was consumed. No significant correlation was found between 36-h urinary excretion of the intravenous calcium tracer and sulfate, sodium, or urine volume. Therefore, calcium from the CS-W was as well absorbed and retained as that from milk, and no calciuric effect of sulfate was found, showing that such mineral waters can be valuable dietary sources of calcium.

Effect of caffeine on circadian excretion of urinary calcium and magnesium.

To determine if later renal conservation occurs in calcium (Ca) and magnesium (Mg) excretion after morning caffeine-induced increases in urinary Ca and Mg excretion. Before-after trial of caffeine abstinance and consumption was conducted on two consecutive days in a metabolic ward while subjects ate a controlled diet containing 11.3 mmol Ca and 12.7 mmol Mg. 17 healthy males and females, ages 17-41 yr volunteered. Two caffeine doses of 3 mg/kg lean body mass caffeine were consumed at 7 and 10 a.m. on second day. Salivary caffeine concentrations and urinary Ca, Mg, sodium and creatinine excretion were measured. Salivary caffeine peaked at 4.7 umol/mL at 11:30 a.m. and declined with a half-life of 7.3 hours. Urinary Ca and Mg were elevated significantly (p = 0.01 and p = 0.04) for six h after the second caffeine dose. Caffeine had no significant effect on urinary calcium or magnesium excretion between 4 p.m. and 1 a.m. Between 1 and 4 a.m., urinary Ca and Mg excretion was decreased after caffeine (p = 0.04 and p = 0.01). Creatinine excretion was not different at any time. Nighttime compensatory renal conservation was insufficient to offset morning caffeine-induced mineral losses, resulting in net 24-hour urinary increases of 0.32 mmol Ca and 0.16 mmol Mg.

Fat emulsions for parenteral nutrition. IV. Lipofundin MCT/LCT regimens for total parenteral nutrition (TPN) with high electrolyte load

The stability of TPN regimens with high electrolyte load based on the emulsions Lipofundin MCT/LCT and Intralipid was investigated. The regimens were of identical composition containing 66.7 mmol/1 monovalent ions and 6.7 mmol/1 divalent ions (3.4 mmol Ca 2+, 3.3 mmol other divalent ions such as Mg 2+). Stability was monitored by microscopy, Coulter counter, photon correlation spectroscopy (PCS) and laser diffractometry. Zeta potential measurements were performed by laser Doppler anemometry (LDA). The Lipofundin regimen was regarded as being stable for 7 days of storage, the Intralipid regimen for at least 2 days but not 7 days. The storage time was limited due to visible heavy creaming and the increased numbers of particles > 4 μm. Microscopic, Coulter counter and PCS two-time-window analysis proved suitable for monitoring the stability. Analysis of the top phase of the regimens proved to be distinctly more sensitive than that of the homogenous mixture of the regimens after shaking. The instabilities observed were mainly attributed to the reduction of the zeta potential to the range of maximum flocculation.

Zinc and copper balances in healthy adult males during and after 17 wk of bed rest

The effects of long-term bed rest on zinc and copper balances were measured in seven healthy men. Volunteers aged 22-54 y (mean +/- SD, 34 +/- 12 y), 168-185 cm in height (173 +/- 5 cm), and 64-86 kg in weight (74 +/- 9 kg) remained on a metabolic ward for 29 wk. Subjects were ambulatory during weeks 1-5, remained in continuous bed rest for weeks 6-22, and were reambulated during weeks 23-29. Copper and zinc were measured in weekly urine and fecal composites. Dietary intakes provided (mean +/- SD) 19.2 +/- 1.2 mumol Cu (1.22 +/- 0.08 mg), 211 +/- 11 mumol Zn (13.81 +/- 0.72 mg), 25.2 +/- 1.2 mmol Ca (1011 +/- 46 mg), 1086 +/- 46 mmol N (15.21 +/- 0.65 g), and 48.1 +/- 1.4 mmol K (1489 +/- 44 mg)/d. Bed rest increased fecal zinc excretion and decreased zinc balance, whereas copper balance was unchanged. Reambulation decreased fecal zinc excretion and increased both zinc and copper balances. These results suggest that during long-term bed rest or space flight, individuals will lose total body zinc and will retain more zinc and copper when they reambulate.

Effects of changes in environmental calcium on prolactin secretion in Japanese eel, Anguilla japonica

Effects of changes in environmental Ca2+ on the secretion of prolactin, a possible hypercalcemic hormone, were examined both in vivo and in vitro in the Japanese ecl, Anguilla japonica. Transfer of seawater- or freshwater-adapted fish to fresh water, fresh water containing 10 mmol Ca2+ · 1-1 sea water, Ca2+-free sea water, or deionized water was accompanied by significant changes in plasma Ca2+ levels after 7 days, except for the fish transferred from fresh water to fresh water and from sea water to sea water. Changes in external Ca2+ concentrations did not affect plasma prolactin levels, although plasma prolactin levels as well as pituitary prolactin contents were significantly greater in fish in a hypotonic environment than those in a hypertonic environment, regardless of the external Ca2+ concentration. Hypercalcemia, induced by removal of the corpuscles of Stannius, did not alter plasma prolactin levles. Incubation of the pituitary in the medium with different Ca2+ concentrations (up to 2.9 mmol·l-1) did not affect the basal release of prolactin, except at an extremely low Ca2+ concentration (less than 0.1 mmol·l-1) where prolactin release was inhibited. Addition of Ca2+ ionophore (A23187) to the medium led to a marked and significant increase in prolactin release, indicating that an increase in intracellular Ca2+ stimulates prolactin release. However, the effect was not specific to prolactin cells; a similar increase was seen in growth hormone release. These results indicate that changes in environmental Ca2+ concentration may not be the primary factor influencing prolactin secretion in the eel; changes in environmental osmolality or Na+ levels seem to be more critical for the regulation of prolactin secretion.

Carbonate dissolution and temporal abundances of Foraminifera in Long Island Sound sediments

The dynamics of benthic Foraminifera assemblages can be used to examine carbonate dissolution processes in nearshore sediments and as a general assay of physical‐chemical factors affecting survival of juvenile benthos. Abundances of total Foraminifera (live and dead) fluctuate regularly throughout the year in Long Island Sound (LIS) mud deposits, with highest numbers in spring‐summer and lowest in winter. Essentially all forams disappear each year. Pore‐water undersaturation with respect to carbonate minerals coincides with periods of rapid disappearance of forams and suggests that these fluctuations reflect a balance between the rate of production‐recruitment and the rates of death and dissolution of the calcareous tests of the animals. Reworking by macrofauna in LIS central basin sediments inhibits accumulation or depletion of pore‐water solutes and is responsible for minimizing pore‐water carbonate saturation states. Quantitative estimates of seasonal patterns of foram dissolution with a simple mass balance model give a minimum average annual flux of Ca2+ in LIS sediments of ∼6 mmol Ca2+ m−2 d−1 (due solely to Foraminifera dissolution). Abandoned tests have a maximum mean residence time of ∼86±13 d. Dissolution‐precipitation of forams may significantly affect benthic ∑CO2 fluxes and likely accounts for a large proportion (>30%) during some seasons or at some locales. Other organisms with carbonate tests of similar size, particularly juvenile bivalves, may also be affected by periods of undersaturated pore waters. Conditions promoting dissolution of tests may represent an important source of mortality for calcareous meiofauna.

Ion movements associated with chorion elevation during egg laying in trout (Oncorhynchus mykiss) in fresh water

Within 1 min of transfer from coelomic fluid to fresh water, eggs of rainbow trout (Oncorhynchus mykiss) underwent a transient loss of Na+ and K+ coupled with an elevation of the chorionic envelope. Both mechanisms were blocked by adding a monovalent cation Li+ or K+ (140 mmol·l-1) to the fresh water, but the divalent ion Mg2+ (100 mmol MgCl2·l-1) or elevating the osmotic pressure to 300 mOsmol·l-1 with glycine had no inhibitory effect. The blocking of Na+ loss occurred at external monovalent cation (LiCl) concentrations above 70 mmol·l-1. A 20-s exposure of eggs to fresh water was sufficient to trigger Na+ loss and chorion elevation, even when the eggs were subsequently transferred to fresh water containing 140 mmol LiCl·l-1. Eggs placed in a medium containing 140 mmol LiCl·l-1 and 2 mmol Ca(NO3)2·l-1 showed chorion elevation and associated Na+ loss after addition of calcium ionophore (20 μmol·l-1 A.23187). This activation by calcium ionophore was supressed in a Ca2+-free medium containing 5 mmol EGTA·l-1.

Effects of oral calcium supplementation on intestinal bile acids and cytolytic activity of fecal water in patients with adenomatous polyps of the colon

Calcium has been proposed to prevent colon cancer in subjects at risk for this tumour. This effect is supposed to be due at least in part to binding the bile acids to calcium, making them insoluble and harmless. To evaluate the effects of oral calcium supplementation on intestinal bile acids, 19 patients with adenomatous colonic polyps were supplemented with 35.5 mmol Ca2+ daily for 12 weeks. Duodenal bile, 24-h feces and 24-h urine were collected before and at the end of the 12-week period. In duodenal bile proportional concentration of cholic acid increased (38 +/- 4 vs. 51 +/- 3%, P < 0.001), whereas that of chenodeoxycholic acid decreased (35 +/- 3 vs. 25 +/- 2%, P < 0.01). Total fecal bile acid excretion increased (950 +/- 126 vs. 1218 +/- 137 mumol 24 h-1, P < 0.01), with proportional concentrations of the main primary and secondary bile acids remaining the same. Cytolytic activity of fecal water, measured by the degree of lysis of erythrocytes by the water, decreased (45 +/- 8 vs. 30 +/- 7%, P < 0.05). Total excretion of calcium increased as expected from the supplementary dose. It is concluded that calcium supplementation markedly affects intestinal bile acids and lytic activity of fecal water and that, in view of similar results during 1-week calcium supplementation in young healthy subjects, these effects remain constant over at least 3 months and occur both in healthy persons and in patients at increased risk for colon cancer.

Ca(2+)-related changes in the mouse sperm capacitation state: a possible role for Ca(2+)-ATPase.

Mammalian spermatozoa require extracellular Ca2+, some of which must be internalized, to undergo complete capacitation. At a critical threshold, a rise in intracellular Ca2+ will trigger acrosomal exocytosis. We used chlortetracycline (CTC) fluorescence patterns to assess changes in the capacitation state of mouse spermatozoa after incubation under various conditions that would affect their intracellular Ca2+ concentrations. Under standard conditions with 1.80 mmol CaCl2l-1 known to support capacitation within 120 min and subsequent fertilization in vitro, a rise in the number of capacitated, acrosome-intact cells (B pattern) was observed over the first 60 min, followed by a decline. A detectable increase in capacitated, acrosome-reacted cells (AR pattern) coincided with the maximum of B pattern cells and a continued rise was observed over the following 60 min. With incubation in 3.60 mmol Ca2+l-1, the rise in AR cells began at 30 min, suggesting that this treatment accelerates capacitation. Introduction of ionophore A23187 at 15 min to cells in standard Ca2+ produced a similar but even more rapid response, with a maximum in B pattern cells and a noticeable rise in AR cells within 10 min. Thus ionophore-treated cells proceed through capacitation, but do so very quickly. However, ionophore in the presence of 90 mumol Ca2+l-1 could promote transition from the uncapacitated F pattern to the capacitated B pattern, but could not trigger acrosomal exocytosis, indicating that the latter requires high extracellular Ca2+. After preincubation in Ca(2+)-deficient medium, most cells exhibited the uncapacitated F pattern and the introduction of millimolar Ca2+ altered this distribution only slowly, over a period of 50 min. In contrast, preincubation in 90 mumol Ca2+l-1 resulted in a minority of F pattern cells and, within 10 min of millimolar Ca2+ introduction, a significant increase in AR cells was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Biochemical and DXA bone densitometry parameters in 316 cases of osteoporosis in Mexico city

The calciuric effects of NaCl and KCl were compared in 11 healthy young women consuming diets containing 600 mg calcium per day. Each subject participated in three treatment periods: (1) control diet containing 44 mmol Na and 64 mmol K, (2) control diet plus 102 mmol NaCl and (3) control diet plus 104 mmol KCl. Urine was collected during the last two days of each treatment period and analyzed for Ca, Na, K and Cl. The NaCl supplement produced calciuria similar to that reported by other researchers. However, the KCl supplement did not cause calciuria. Subjects receiving the KCl excreted 5.2±0.4 mmol Ca compared to 7.0±0.4 mmol Ca during NaCl supplementation and 5.9±0.6 mmol Ca during the control period. This suggests that the current practice of replacing some NaCl in food processing, or in salt substitutes, with KCl will decrease the amount of sodium consumed by the general population without contributing to calcium excretion.

Bone histomorphometry and temporal course of serum calcium after acute intravenous administration of Salmon Calcitonin in patients with renal osteodistrophy

The calciuric effects of NaCl and KCl were compared in 11 healthy young women consuming diets containing 600 mg calcium per day. Each subject participated in three treatment periods: (1) control diet containing 44 mmol Na and 64 mmol K, (2) control diet plus 102 mmol NaCl and (3) control diet plus 104 mmol KCl. Urine was collected during the last two days of each treatment period and analyzed for Ca, Na, K and Cl. The NaCl supplement produced calciuria similar to that reported by other researchers. However, the KCl supplement did not cause calciuria. Subjects receiving the KCl excreted 5.2±0.4 mmol Ca compared to 7.0±0.4 mmol Ca during NaCl supplementation and 5.9±0.6 mmol Ca during the control period. This suggests that the current practice of replacing some NaCl in food processing, or in salt substitutes, with KCl will decrease the amount of sodium consumed by the general population without contributing to calcium excretion.

The influence of NaCl and KCl on urinary calcium excretion in healthy young women

The calciuric effects of NaCl and KCl were compared in 11 healthy young women consuming diets containing 600 mg calcium per day. Each subject participated in three treatment periods: (1) control diet containing 44 mmol Na and 64 mmol K, (2) control diet plus 102 mmol NaCl and (3) control diet plus 104 mmol KCl. Urine was collected during the last two days of each treatment period and analyzed for Ca, Na, K and Cl. The NaCl supplement produced calciuria similar to that reported by other researchers. However, the KCl supplement did not cause calciuria. Subjects receiving the KCl excreted 5.2±0.4 mmol Ca compared to 7.0±0.4 mmol Ca during NaCl supplementation and 5.9±0.6 mmol Ca during the control period. This suggests that the current practice of replacing some NaCl in food processing, or in salt substitutes, with KCl will decrease the amount of sodium consumed by the general population without contributing to calcium excretion.

Release of proinsulin from the human fetal β cell

beta cells in the human fetal pancreas are immature in that they release little or no insulin in response to nutrients, such as glucose. The aim of this study was to examine further the immaturity of these cells, specifically regarding the storage and release of the precursor of insulin, proinsulin. Explants of human fetal pancreas were cultured in vitro for 3 weeks. Levels of proinsulin remained relatively constant throughout at 0.04 +/- 0.002 (S.E.M.) pmol/mg per day with a molar ratio of proinsulin to insulin of 2.2 +/- 0.11%. This low ratio was slightly greater than that observed in culture medium conditioned by adult human islets (0.3 +/- 0.1%), but similar to that found in acid-ethanol extracts of cultured explants (1.4 +/- 0.3%). Passaging of human fetal pancreas for 3 months in diabetic nude mice, which should have caused some maturation of the fetal beta cell, did not change the proportion of proinsulin present. Culture of explants in the presence of 12-O-tetra-decanoylphorbol-13-acetate resulted in some inhibition of proinsulin release, but much less than that for insulin, so that the molar ratio increased to 15.4 +/- 1.6% from the control 3.5 +/- 0.3%. Static stimulation of cultured explants with 10 mmol Ca2+/l, 10 mmol theophylline/l, and these two agents together caused 15-, 4- and 10-fold enhancement respectively of proinsulin release; glucose, leucine, arginine and KCl had no effect. In contrast, all these agents caused significant insulin release, the last four to a much smaller extent (less than or equal to three fold) than the first three (10-, 19- and 65-fold respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of mercury on unidirectional sodium and calcium influx in Asellus aquaticus.

The effect of mercuric chloride (HgCl2) and monomethyl mercury chloride (CH3HgCl) on unidirectional 22Na and 45Ca influx were measured in the freshwater isopod Asellus aquaticus. Flux measurements involved short-term (20 min) exposure to 22Na or 45Ca following 2 h pre-exposure to Hg. Experiments were conducted at two different Na and Ca concentrations, 0.025 mmol L-1 and 0.25 mmol L-1. HgCl2 and CH3HgCl inhibited Na influx at both Na concentrations although Na influx at 0.25 mmol L-1 was always higher. This reflected the uptake kinetics of the Na pump which was determined to be saturable with a kmax values of 32 mumol Na g-1 h-1 and a Km value of 0.8 mmol L-1. CH3HgCl generally resulted in relatively greater inhibition of Na influx. At 0.025 mmol Na L-1 all CH3HgCl concentrations tested were inhibitory to Na influx, i.e., the lowest observed effect concentration (LOEC) was less than 0.04 mumol L-1. Ca influx was inhibited by HgCl2 at all concentrations tested (LOEC less than 0.04). The degree of inhibition was unaffected by Ca concentration, which was seen as evidence for non-competitive inhibition. However, CH3HgCl, which inhibited Ca influx from 0.025 mmol Ca L-1 by greater than 68% at molar Hg concentrations greater than or equal to 1 mumol L-1 showed no significant inhibitory affect at 0.25 mmol Ca L-1. Elimination of CH3HgCl inhibition at the higher Ca concentration suggests competition in this case, possibly at the level of access to the Ca pump.

Efficacy of calcium glycerophosphate vs conventional mineral salts for total parenteral nutrition in low-birth-weight infants: a randomized clinical trial

To test the efficacy of calcium glycerophosphate (CaGlyP) vs the conventional mineral salts, calcium gluconate plus KH2PO4 + K2HPO4 (CaGluc + P), in promoting mineral retention, 72-h mineral balance, biochemical status, net acid excretion, and growth were assessed in 16 low-birth-weight infants receiving total parenteral nutrition (TPN) containing approximately 1.5 mmol Ca and P.kg-1.d-1 for 5 d. Net retentions of calcium (1.2 +/- 0.2 vs 1.0 +/- 0.2 mmol.kg-1.d-1, means +/- SD) and phosphorus (1.1 +/- 0.3 vs 0.8 +/- 0.3 mmol.kg-1.d-1) from CaGluc + P vs CaGlyP, respectively, were similar, as were retentions of magnesium and sodium, urinary pH, and net acid excretion. Plasma ionized calcium, inorganic phosphorus, alkaline phosphatase, and osteocalcin were normal and not different between groups. CaGlyP is as effective as CaGluc + P in promoting mineral retention and normal mineral homeostasis. However, at intakes of less than or equal to 1.5 mmol Ca and P.kg-1.d-1 from either mineral salt, retention represented only 60% and 45%, respectively, of the predicted intrauterine accretion for calcium and phosphorus. Larger intakes permitted by the more-soluble CaGlyP may be desirable for infants receiving TPN.

Calcium, magnesium, zinc, and iron balances in young women: effects of a low-phytate barley-fiber concentrate

The effects of a low-phytate barley-fiber concentrate on calcium, magnesium, and zinc balances and on apparent iron absorption were measured by balance experiments. During the three experimental periods of 22 d each, all subjects consumed the basal diet alone, the basal diet with 15 g barley fiber (high-fiber, high-protein diet), and a modified basal diet containing less protein with 15 g barley fiber (high-fiber, low-protein diet), respectively. The mean daily intake of the cations was 24.4, 25.4, and 22.9 mmol Ca; 10.4, 10.1, and 10.0 mmol Mg; 165.2, 166.8, and 119.3 mumol Zn; and 154.0, 186.2, and 154.0 mumol Fe, respectively. Mean balances were 0.2, 1.9, and -0.8 mmol Ca; 0.3, -0.2; and -0.5 mmol Mg; 3.0, -4.6, and -18.4 mumol Zn. The mean apparent iron absorption was 16.1, 5.4, and -23.2 mumol when these three diets, respectively, were consumed.

Effects of Bicarbonate Supplementation on Urinary Mineral Excretion During Very Low Energy Diets

Metabolic acidosis is associated with increased calciuria and ammoniagenesis. This study evaluated the effects of oral sodium bicarbonate (NaHCO3) or combined potassium bicarbonate-calcium carbonate supplementation on urinary mineral excretion during the ketoacidosis of a very-low-energy protein diet. Seventeen healthy obese subjects (BMI: 37.5 +/- 3.2 kg/m2, weight: 100 +/- 3 kg) were given a 1.72 MJ all protein (93 g) liquid formula and a multivitamin-mineral supplement daily for 3 weeks. Subjects in groups 1 (n = 6) and 2 (n = 5) received 16 mmol KCl. In addition, subjects in group 1 received 60 mmol Na+ daily as sodium chloride, subjects in group 2, 60 mmol Na+ as NaHCO3. The subjects in group 3 (n = 6) were given 32 mmol K+ as bicarbonate and 16 mmol Ca++ as carbonate daily. Metabolic acidosis was prevented in groups 2 and 3 with bicarbonate and bicarbonate-carbonate administration. This was reflected in significant curtailment of the augmented ammonium nitrogen excretion found in group 1. The additional oral K+ in group 3 improved K+ balance and probably also inhibited ammoniagenesis. Urine calcium was greater (p less than 0.04) in group 1 subjects, but similar in groups 2 and 3, despite higher calcium intake in group 3. Urinary phosphorus decreased with time in all groups, but more so in the group 2 subjects who received NaHCO3. Acidosis was associated with the reverse effect on urinary magnesium, which decreased in group 1 subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium Acetate Control of Serum Phosphorus in Hemodialysis Patients

Calcium acetate has many characteristics of an ideal phosphorus binder. It is a readily soluble salt that avidly binds phosphorus in vitro at pH 5 and above. One-dose/one-meal balance studies show it to be more potent than calcium carbonate or calcium citrate. We studied chronic (3-month) phosphorus binding with calcium acetate in 91 hyperphosphatemic dialysis patients at four different centers. All phosphorus binders were stopped for 2 weeks. Calcium acetate at an initial dose of 8.11 mmol (325 mg Ca2+) per meal was then used as the only phosphorus binder. Dose was adjusted to attempt control of predialysis phosphorus level less than 1.78 mmol/L (5.5 mg/100 mL). Final calcium acetate dose was 14.6 mmol (586 mg) Ca2+ per meal. Sixteen patients developed mild transient hypercalcemia (mean, 2.84 mmol/L [11.4 mg/dL]. Initial phosphorus values in mmol/L (mg/dL) were 2.39 (7.4); at 1 month, 1.91 (5.9); and at 3 months, 1.68 (5.2). Initial calcium values in mmol/L (mg/dL) were 2.22 (8.9); at 1 month, 2.37 (9.5); and at 3 months, 2.42 (9.7). Initial aluminum values in mumol/L (micrograms/L) were 2.99 (80.7); and at 3 months were 2.54 (68.4). Initial C-terminal parathyroid hormone (C-PTH) values in ng/mL were 14.6; at 1 month, 11.9; and at 3 months, 13.2. Sixty-nine patients then entered a double-blind study. Phosphorus binders were stopped for 1 week. Calcium acetate (at a dose established in a prior study) or placebo was then administered for 2 weeks. Next, patients were crossed to the opposite regimen for 2 weeks. Initial phosphorus was 2.36 mmol/L (7.3 mg/100 mL) and calcium 2.22 mmol/L (8.9 mg/100 mL).(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma Sodium-Potassium ATPase Inhibition Activity in Low- and Normal-Renin Hypertension

Thirty-seven subjects with low- and normal-renin hypertension (plasma renin activity less than 0.45 ng/L/sec on a 100 mmol Na diet) were studied on a 10 and 100 mmol sodium diet (100 mmol K and 25 mmol Ca) to examine the effect of varied sodium intake on plasma Na,K-ATPase inhibitory activity (NKAIA) (% inhibition). On the 10 mmol Na diet, plasma NKAIA correlated with mean arterial pressure (MAP) (r = 0.384, P = .019). On the 100 mmol Na diet, plasma NKAIA correlated with daily urinary sodium excretion (r = 0.384, P = .019). With the increase in sodium intake, the mean change in MAP was 0.5 +/- 7.8 mm Hg (range -12.7 to 16.3) and the mean change in plasma NKAIA was -4.2 +/- 11.2% inhibition (range -37.5 to 16). The change in MAP was correlated to the change in plasma NKAIA (r = 0.384, P = .019). Plasma NKAIA is related to mean arterial pressure or urinary sodium excretion depending on the dietary sodium intake, and is related to sodium-induced changes in MAP in low and normal renin hypertensive patients.