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)

Comparison of an orally administered gastrointestinal lavage solution with traditional enema administration as preparation for colonoscopy in dogs.

Forty dogs were randomly assigned to be given either multiple enemas (group A) or orally administered lavage solution (group B) before colonoscopy. Dogs of group A (n = 20) were given 3 large-volume warm-water enemas 6 hours apart, with the last enema given 9 to 15 hours before colonoscopy. Dogs of group B (n = 20) were given a total dose of 50 ml of the lavage solution/kg of body weight through an orogastric tube. The lavage solution was administered in 2 doses of 25 ml/kg given 1 hour apart, 12 to 18 hours before colonoscopy. Dogs were monitored for changes in body weight and in serum sodium, potassium, chloride, calcium, phosphate, urea nitrogen, creatinine, and total CO2 concentrations. Colonoscopy was performed on dogs under general anesthesia by an investigator blinded as to the method of preparation, and the quality of preparation was subjectively evaluated. The quality of colon preparation was significantly (P less than 0.005) better after administration of oral lavage solution, compared with that after multiple enemas. There were minimal changes in laboratory values, side-effects were minimal, and biopsy specimen artifacts were not seen. Because proper patient preparation is necessary for complete colonoscopic examination, results suggested that an orally administered polyethylene glycol-containing electrolyte solution is preferable to administration of multiple enemas in preparing dogs for colonoscopy.

Mg++-sensitivity of neuromuscular transmission in two crustaceans: correlation with blood Mg++ levels.

Neuromuscular transmission was measured in muscles of spider crabs (Hyas areneus) and lobsters (Homarus americanus). Solutions containing 40 and 10 mM/1 Mg++, which were approximately the same as those measured in the blood of Hyas and Homarus, respectively, were used to soak the preparations prior to testing. In Homarus, neuromuscular transmission was severely depressed by 40 mM Mg++. In spider crabs, neuromuscular transmission was not severely depressed. Although the amount of transmitter released by nerve impulses was reduced, total membrane depolarization during trains of impulses was not reduced because a compensating increase in muscle fiber membrane resistance occurred in Hyas preparations exposed to M Mg++. Hyas, but not Homarus, is physiologically adapted to function at relatively high blood Mg++ concentrations.