A computerized system is described, combining automatic collection of urine in short intervals (minutes) over long periods (days) and recordings of body temperature, MABP, and heart rate in chronically instrumented conscious dogs. During the studies the dogs are housed in metabolic cages. Indwelling catheters and electrical wires are connected to a specially designed swivel and directed out of the cage to the next room. Infusions, blood sampling, and monitoring can be performed from this room without disturbance to the dogs. Three examples of recordings are given. In one of these examples the sodium excretion patterns on 5 consecutive days under continuous saline infusion in one dog is evaluated. Urine was collected every 20 min. Sodium excretion showed cyclic variations. Fourier analysis exhibited 18-h periods and 4- to 8-h periods. The described system renders, e.g., coherent time series analysis possible for a variety of simultaneously recorded physiological variables and may thus acquire considerable importance for integrative physiology.

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SummaryCatheter-related infections pose a hazard to both humans and laboratory animals. The aim of this study was to develop a technique preventing bacterial colonization of intravascular catheters.In 27 dogs a total of 70 catheters were implanted. On an average catheters were used for 207 days.Three protocols were compared: (1) flushing the catheters with a heparinized solution; (2) filling only the catheter lumen with achymotrypsin solution (225 units/ml); (3) filling only the catheter lumen with a solution containing a mixture of the aminoglycoside antibiotic gentamicin (20 mg/ml) and chymotrypsin (225 units/mI).Catheter fillings were always withdrawn before catheter use. Catheter exit sites were all treated with povidone iodine ointment once a day. Body temperatures and weights were recorded, bacteriological and electron microscopical examinations of catheters performed.Without gentamicin filling all catheters were colonized after a few weeks. The dogs showed clinical signs of chronic bacteraemia. Gentamicin filling eradicated colonization. No further bacteraemia was observed.We conclude that filling only the catheter lumen with a concentrated solution of chymotrypsin and gentamicin, combined with measures to prevent infections via the subcutaneous catheter tunnel, is an effective and safe technique to prevent catheter-related infections.

The existence of urinary excretion rhythms in dogs, which is a matter of controversy, was investigated under strictly controlled intake and environmental conditions. In seven conscious dogs, 14.5 mmol Na, 3.55 mmol K, and 91 ml H2O.kg body wt-1.24 h-1 were either administered with food at 8:30 A.M. or were continuously infused at 2 consecutive days. During these 3 days, automatized 20-min urine collections, mean arterial blood pressure (MABP), and heart rate (HR) recordings were performed without disturbing the dogs. Fundamental and partial periodicities, the noise component of urinary sodium excretion (UNaV), MABP, and HR were analyzed using a method derived from Fourier and Cosinor analysis. Oral intake (OI) leads to powerful 24-h periodicities in all dogs and seems to synchronize UNaV. UNaV on OI peaked between 1 and 3 P.M. Under the infusion regimen, signs of nonstationary rhythms and desynchronization predominated. UNaV under the infusion regimen could be separated into two components: a rather constant component continuously excreted and superimposed to this an oscillating component. No direct coupling between UNaV and MABP periodicities could be demonstrated. On OI, an increase in HR seems to advance the peak UNaV in the postprandial period. HR and MABP signals were both superimposed with noise. We conclude that UNaV rhythms are present in dogs. They are considerably more pronounced on OI.

The diurnal time course of urinary flow rate (UV), urinary sodium (U_NaV), and potassium (U_KV) excretion, and of hormones such as atrial natriuretic peptide (ANP) and aldosterone, was investigated during 5 days of continuous captopril infusion (15 µg · kg body weigth^-1 · min^-1) in 4 conscious dogs on a high sodium diet (14.5 mmol Na·kg body weigth^-1 24 h^-1). All food and water was given once daily at 8.30 a.m. On the control day and on days 1, 3, and 5 of·captopril infusion, urine was collected by an automated system at 20-min intervals over 24 h, blood was taken every 4 h. Mean arterial blood pressure (MABP) and heart rate were evaluated as 5-min averages. Time courses of U_NaV, UV, and UKV were compared with the individual control day without captopril. With captopril, 24-hour balances for Na and H₂0 were slightly negative, while the K balance was slightly positive for 2-3 days. Thereafter, all 24-hour balances were restored. MABP continued to decrease even after Na and water intake and output had come into balance again. Captopril treatment changed the diurnal excretion pattern for U_NaV and UV characteristically. In the postprandial period until 5 p.m., less Na and urine were excreted than on the control day, whereas during the evening and night more Na and urine were excreted. The changes in the excretion pattern persisted for the entire observation period. The results indicate that disturbances in the regulating systems, induced by converting-enzyme blockade, bring about complex reactions of, e.g., MABP ANP and aldosterone that finally restore Na and water 24-hour input/output balances.

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1. Automated, sequential, 20 min urine collections were made to provide a record of diurnal variations of urinary sodium excretion (UNaV) in seven dogs, in which the same daily intake of sodium, potassium and water was administered, at first orally (between 08.30 and 08.50 h) on day 1 and then by i.v. infusion at a constant rate on days 2 and 3. This basic protocol was employed for two different levels of sodium intake: normal (NSI;2'5 mmol (kg body wt)1 (24 h)-1) and high (HSI; 14-5 mmol (kg body wt)1 (24 h)-1).2. The aims were: firstly, to establish the diurnal pattern of UNaV under these circumstances; secondly, to find out whether the quantity of sodium administered influences this diurnal pattern; and thirdly, to distinguish endogenous fluctuations from intake-dependent components in the UNa V excretion patterns.3. On day 1 (oral intake) all dogs exhibited a similar excretion pattern, which peaked between 13.00 and 15.00 h on both diets and then diminished again over the remainder of the 24 h period. 4. On days 2 and 3 (infusion) UNa V fluctuated within a considerable range. 5. On HSI, the maximal UNa V rates on day 1 were about double those observed on infusion days. On HSI, UNa V during infusion days seems to consist of a constant basal component of about 5-6 #smol (kg body wt)f min' upon which a fluctuating component is superimposed. The basal component may be a reactive homeostatic response to the high sodium intake, whereas the superimposed fluctuating component may reflect endogenous variations.6. On NSI, mean UNa V, variance and peak UNaV were nearly the same during oral intake and on infusion days. Thus, on NSI, UNa V variations seem to be caused primarily by endogenous mechanisms.

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