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It has been postulated recently that renal bicarbonate reabsorption is entirely dependent on the exchange of hydrogen ions, derived from the dissociation of carbonic acid within the cells of the renal tubule, for the fixed base of filtered bicarbonate in the tubular urine (1-3). According to this theory, an elevation of the CO2 tension of the extracellular fluid results in an increase in the rate of bicarbonate reabsorption because it leads to an increase in the rate of hydrogen ion secretion.Earlier studies, however, indicate that chloride reabsorption may interfere with bicarbonate reabsorption presumably because of competition between these two ions for some common transport mechanism in the proximal tubule (4). Since plasma pCO2 was apparently within normal range in those experiments, it was thought of interest to study the effect of hyperchloremia on bicarbonate reabsorption in the presence of an elevated extracellular pCO2.Our results indicate that under these circumstances the rate of bicarbonate reabsorption does not depend entirely on the CO2 tension, but may, in part, depend upon the rate of chloride ion reabsorption. METHODSNormal adult mongrel female dogs were anesthetized by the intravenous administration of 0.46 to 0.62 mg. of sodium pentobarbital per kilogram of body weight. The trachea was cannulated with a "Y"-shaped glass tube, the two free arms of which served as inspiratory and expiratory airways by means of flutter valves. The animals breathed spontaneously throughout the entire experiment. The abdomen was opened by a midline in-1 Supported by grants-in-aid from the New York Heart Association and the American Heart Association.2Fellow of the New York Heart Association.3 Frances H. Zabriskie Fellow, St. Luke's Hospital.cision and each ureter cannulated with a polyethylene tube. The abdomen was then closed by a continuous silk suture and the polyethylene tubes brought through the suture line, care being taken not to kink the ureters and tubes. Urine was collected directly under mineral oil contained in a graduated cylinder.During the successive periods of study, the dog breathed first room air, then a mixture of CO, and air containing 10 per cent of CO,,The different solutions were administered at desired rates by means of a constant-speed Bowman pump via a cannulated brachial vein. As the operative procedure was begun, the animal was given intravenously within a 5 to 24-minute period 400 ml. of a 0.15 molar sodium bicarbonate solution containing 0.375 Gram per cent of creatinine. Then a sustaining infusion containing from 0.93 Gram per cent of NaHCO, to 1.175 Gram per cent of NaHCO, (0.11 to 0.14 molar solution) was administered at rates varying between 6.4 and 18.5 ml. per minute. This infusion also contained an amount of creatinine such that the dog received 15 mgm. of creatinine per minute. When the operative procedures were completed, a fifteen to thirty-minute equilibration period was allowed. Then control determinations were made, the animal breathing room air and receiving the sustaini...

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The US Pharmacopeia gives recommendations for the storage of pharmaceuticals in terms of mean kinetic temperature (MKT). This study's goal was to determine if color-changing time–temperature indicator (TTI) labels can reliably monitor the MKTs of medications used in ambulances. TTI labels and miniature electronic temperature recorders were placed into the drug storage boxes in five advanced life support units over 12 summer weeks in 1995 and in three advanced life support units over 4 weeks the following winter. The electronic temperature recorders measured temperatures several times per hour, and the color changes of the TTI labels were analyzed periodically. The MKTs calculated from the TTI labels differed from those calculated from the electronic temperature recorders in all cases by less than 1° C. The authors concluded that TTIs can accurately measure the MKTs of medications used in ambulances. A TTI label on each medication container may help insure that drugs are not damaged by temperture conditions.

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